WO2012090566A1

WO2012090566A1 - Heat insulation material and production method for same

Info

Publication number: WO2012090566A1
Application number: PCT/JP2011/073003
Authority: WO
Inventors: ちひろ飯塚; 新納　英明
Original assignee: 旭化成ケミカルズ株式会社
Priority date: 2010-12-27
Filing date: 2011-10-05
Publication date: 2012-07-05
Also published as: TW201226362A; KR20130095298A; KR101506413B1; TWI457311B

Abstract

The purpose of the present invention is to provide: a heat insulation material that takes into account issues with conventional technology, is unlikely to collapse or deform when compressed, is capable of being cut or otherwise shaped without collapsing, and has heat insulation properties; and a highly productive production method for the heat insulation material. The heat insulation material is formed including silica and/or aluminum, includes a plurality of small particles with a particle diameter (D_s) of 5-30 nm, has a maximum load of 0.7 MPa min. at 0-5% compression, and has a heat transfer rate of 0.05 W/m·K max., at 30°C.

Description

Insulating material and manufacturing method thereof

The present invention relates to a heat insulating material and a method for manufacturing the heat insulating material.

The average free path of air molecules at room temperature is about 100 nm. Therefore, in a porous body having voids with a diameter of 100 nm or less, convection due to air and heat transfer due to conduction are suppressed, and such a porous body exhibits an excellent heat insulating action.

In accordance with the principle of heat insulation, it is known that ultrafine particles have a low thermal conductivity and are suitable as a heat insulating material, and it is known that a heat insulating material having an extremely low thermal conductivity can be obtained by a microporous structure. For example, Patent Document 1 describes a heat insulating material obtained by independently forming an ultrafine powder of silica into a porous body. The heat insulating material has a bulk density of 0.2 to 1.5 g / cm ³ and a BET specific surface area. Is 15 to 400 m ² / g, the average particle diameter is 0.001 to 0.5 μm, the total pore volume is 0.3 to 4 cm ³ / g, and the total pores of pores having an average pore diameter of 1 μm or less The cumulative pore volume of pores whose volume is 70% or more of the cumulative pore volume in the molded body and whose average pore diameter is 0.1 μm or less is 10% or more of the cumulative pore volume in the molded body. In Patent Document 2, porous particles are formed by coating particles made of a radiation absorption / scattering material or the like with ultrafine particles associated in a ring shape or a spiral shape so that the inner diameter of the ring becomes 0.1 μm or less. Is described as a method for producing a heat insulating material by pressure-molding this precursor into a powder of a heat insulating material precursor by mixing it with a porous coated fiber formed in the same manner as inorganic fibers or porous coated particles. ing. Patent Document 3 discloses a microporous body composed of two or more kinds of fine particles having different primary particle diameters. In Non-Patent Document 1 below, fumed silica is selected as a material having low thermal conductivity, and ceramic fiber and heat resistance of a special particle size and particle size distribution are used as an infrared opacifier in order to reduce infrared transmission. A method is disclosed in which a metal oxide is blended and a hole is provided so as to reduce the cross-sectional area of the heat passage.

JP 2007-169158 A Japanese Patent No. 4367612 JP-A-1-103968 Special table 2008-542592

Certainly, the microporous structure contributes to reducing the heat conduction of the heat insulating material, but increasing the ratio of the holes leads to reducing the strength of the heat insulating material. On the other hand, when analyzing the purpose of use of the heat insulating material, it is desirable to process it into a complicated shape depending on the application, but if the strength of the heat insulating material is not sufficient, it cannot withstand processing such as cutting, drilling, punching, etc. There is a problem. According to a study by the present inventor, when processing such as cutting, it is necessary that the load resistance at the time of compression by 5% is large. Specifically, the maximum load at a compression rate of 0 to 5% is required. It was found necessary to be 0.7 MPa or more.

However, the microtherm described in Non-Patent Document 1 (trade name, manufactured by Nippon Microtherm Co., Ltd.) is a panel type having a density of 200 to 275 kg / m ^{3 and} the load at a compression rate of 5% is 2 kg / cm ^2. It is. Further, for the same type of insulation from the graph listed (Non-Patent Document # 1 "compression resistant FIG Microtherm"), to about 10% compressive deformation at a load of about 4.5 kg / cm ² When the inventor studied, the heat insulating material described in Non-Patent Document 1 did not have sufficient strength, and it was easy to collapse when trying to cut.

Non-Patent Document 2 describes that a microtherm is a solid or flexible plate-like molded body, and the compression strength at 5% compression is 75 to 600 kN / m ² depending on the density. In addition, since microtherm is a material whose deformation point is not clear and deformation occurs, the strength test method is described as measuring the relationship between compressive load and deformation rate.

Non-Patent Document 2 introduces a strength measurement example (ASTM Test Method C 165) based on a standardized measurement standard of ASTM (American Society for Testing for Materials and Materials) compression strength of ASTM (American Society for Testing and Materials). . According to this, heat insulation is measured with a normal testing machine, but it does not show a pattern that collapses with a certain stress, so it is described that a load-deformation curve is drawn and compared with a load at a certain deformation rate. Yes. As described above, when the heat insulating material is greatly compressed and deformed by the load, the heat insulating performance is likely to be deteriorated, and a gap is generated due to the compressive deformation, the strength of the portion is decreased, and the material is easily collapsed. Problems may arise. Although the heat insulating materials described in Patent Documents 1 to 3 are excellent in terms of heat insulating performance, the compression strength is insufficient, and the possibility of compressive deformation during use of the heat insulating material is very high. Furthermore, when industrially using a heat insulating material mainly composed of ultrafine particles as described in Patent Documents 1 to 3, the heat insulating material mainly composed of ultrafine particles is very bulky and has a loosely packed bulk density. Due to the small size, the following problems occur. For example, when molding by pressure, it is very easy to scatter and difficult to fill the mold, and when the heat insulating material aggregates in the supply process to the mold, the bulk density of the loose filling depends on the remaining amount of the heat insulating material in the storage tank hopper. Because it changes, stable continuous supply may be difficult. Such agglomeration of the forming raw material may lead to insufficient filling of the mold, resulting in a significant reduction in productivity.

Furthermore, although the powdery heat insulating material needs to deaerate air at the time of pressure molding, it has a large amount of air in advance and, as described in Patent Document 3, contains ultrafine particles as a main component. Since the porous body has a small pore diameter, it tends to be required for a long time for deaeration by reduced pressure or the like, and the productivity is low. In addition, the stroke tends to be large when pressure-molding a bulky heat insulating material mainly composed of ultrafine particles. When the stroke is large, the powder in the vicinity of the pressurization location is likely to become insufficient as the distance from the pressurization location increases even if the powder is sufficiently consolidated. For example, when the mold is filled with powder and pressed from above, the upper part of the powder that is filled and pressed in the mold is sufficiently consolidated, but the lower part, that is, the vicinity of the bottom of the mold is consolidated. Tends to be insufficient. If the compaction of the powder is uneven, lamination is likely to occur when the pressure is released. Lamination refers to a phenomenon in which a molded product obtained by pressure molding is peeled into two or more layers mainly in the thickness direction. If such delamination occurs, it cannot be handled as a product, and the yield decreases, which is not preferable.

On the other hand, Patent Document 4 includes a plurality of glass particles and a binder composition for melting glass when the heat insulating compound is exposed to a temperature higher than 1000 ° C., and has a rubber-like layered ceramic-like structure. Insulating composites with low porosity are disclosed. Although the heat insulation composite currently disclosed by patent document 4 is hard to compress-deform, it cannot be said that heat insulation performance is enough.

The present invention has been made in view of such problems of the prior art, is not easily collapsed or deformed during compression, can be processed without cutting and can be shaped and cut, and has heat insulation properties. It aims at providing the manufacturing method of the heat insulating material excellent in material and productivity.

As a result of intensive studies to solve the above problems, the present inventor is a heat insulating material containing silica and / or alumina, which contains small particles of a specific particle diameter and exhibits a specific compressive strength. It has been found that high heat insulation is exhibited even in applications where the load is large, and the present invention has been completed. That is, the present invention is as follows.

The present invention is molded include silica and / or aluminum, it comprises a plurality of small particles having a particle diameter _{D S} is 5nm or more 30nm or less, the maximum load in the compression ratio 0-5% is 0.7MPa or more Provided is a heat insulating material having a thermal conductivity at 30 ° C. of 0.05 W / m · K or less.

The heat insulating material of the present invention preferably has a bulk density of 0.2 g / cm ³ or more and 1.5 g / cm ³ or less.

The heat insulating material of the present invention preferably has a pore volume of 0.5 mL / g or more and 2 mL / g or less.

The heat insulating material of the present invention has an integrated fine pore diameter of 0.05 μm or more and 0.5 μm or less with respect to an integrated pore volume V _0.003 of pores having a pore diameter of _0.003 μm or more and 150 μm or less. The ratio R of the pore volume V is preferably 70% or more.

The heat insulating material of the present invention further contains infrared opaque particles, and preferably has a thermal conductivity at 800 ° C. of 0.2 W / m · K or less.

The infrared opaque particles contained in the heat insulating material of the present invention have an average particle size of 0.5 μm or more and 30 μm or less, and the content of the infrared opaque particles is 0.1 based on the total mass of the heat insulating material. It is preferable that they are mass% or more and 39.5 mass% or less.

The heat insulating material of the present invention includes silica and / or aluminum, and includes a plurality of large particles having a particle diameter _DL of 50 nm to 100 μm, and the mass of the large particles relative to the sum of the mass of the small particles and the mass of the large particles The ratio _RL is preferably 60% by mass or more and 90% by mass or less.

The heat insulating material of the present invention includes at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements and germanium, and at least selected from the group consisting of alkali metal elements and alkaline earth metals. When containing one element, the content is 0.005 mass% or more and 5 mass% or less based on the total mass of the heat insulating material, and when containing germanium, the content is the total of the heat insulating material. It is preferable that it is 10 mass ppm or more and 1000 mass ppm or less on the basis of mass.

It is preferable that at least one element selected from the group consisting of the above alkali metal elements, alkaline earth metal elements and germanium is contained in the large particles in the heat insulating material of the present invention.

The heat insulating material of the present invention further contains inorganic fibers, and the content of the inorganic fibers is preferably more than 0% by mass and 20% by mass or less based on the total mass of the heat insulating material.

The heat insulating material of the present invention contains phosphorus (P), and the content of phosphorus (P) is preferably 0.002% by mass or more and 6% by mass or less based on the total mass of the heat insulating material.

The heat insulating material of the present invention contains iron (Fe), and the content of iron (Fe) is preferably 0.002% by mass or more and 6% by mass or less based on the total mass of the heat insulating material.

The present invention also provides the above heat insulating material housed in a jacket material.

It is preferable that the jacket material contains inorganic fibers or the jacket material is a resin film.

The present invention is also a method for producing the above-described heat insulating material, wherein a housing step of housing an inorganic mixture containing silica and / or alumina and containing small particles having an average particle diameter of 5 nm to 30 nm in a mold, and A molding step for molding the inorganic mixture, and the molding step is (a) a step of heating the inorganic mixture to 400 ° C. or higher while pressurizing it with a mold, or (b) after the inorganic mixture is molded by pressurization. A method for producing a heat insulating material, which is a step of performing a heat treatment at a temperature of 400 ° C. or higher.

The inorganic mixture preferably contains silica and / or alumina, and further contains large particles having an average particle size of 50 nm to 100 μm.

In the method for producing a heat insulating material according to the present invention, the ratio _RL of the mass of the large particles to the sum of the mass of the small particles and the mass of the large particles is mixed at 60 mass% to 90 mass% to obtain an inorganic mixture. It is preferable to further have.

The large particles preferably contain at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and germanium.

In the molding step, it is preferable to set the molding pressure so that the bulk density of the molded heat insulating material is 0.2 g / cm ³ or more and 1.5 g / cm ³ or less.

In the method for manufacturing a heat insulating material of the present invention, it is preferable that the method further includes a cutting step of cutting a part of the molded body obtained in the molding step.

According to the present invention, it is possible to provide a heat insulating material and a method for manufacturing the heat insulating material that are unlikely to be collapsed or deformed during compression and that can be cut and shaped without collapsing.

It is a graph which shows the relationship between loosely packed bulk density and large particle content _RL . It is a photograph which shows an example of the measuring apparatus of loose filling bulk density. It is a cross-sectional schematic diagram of a heat insulating material provided with the jacket material which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram of the small particle and large particle which the heat insulating material which concerns on one Embodiment of this invention contains.

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[1] Heat insulating material [1-1] Silica, alumina The heat insulating material of the present embodiment includes a plurality of small particles of silica and / or alumina. The component which does not satisfy the size of “small particles” described later may contain silica and / or alumina, and the content of silica and / or alumina in the heat insulating material (the small particles and the silica in the components other than the small particles and It is preferable that the mass of alumina (which is expressed by the ratio of the mass to the mass of the heat insulating material) is 50% by mass or more because heat transfer by solid conduction is small. Hereinafter, silica and / or alumina particles that do not satisfy the sizes of “small particles” and “small particles” are collectively referred to as “silica particles” and “alumina particles”.

It is more preferable that the content of silica particles and / or alumina particles is 75% by mass or more of the powder because the adhesion between the powders increases and the powder scattering decreases. Note that the present specification silica particles, other particles comprised of component represented by the composition formula SiO _2, refers to a material containing SiO _2, a metal component or the like in addition to SiO _2, containing other inorganic compounds Includes particles. In addition to pure silicon dioxide, the silica particles may contain salts and complex oxides with Si and various other elements, or may contain hydrated oxides such as hydroxides. It may have a silanol group. In the present specification, the alumina particles, other particles consisting of only the component represented by a composition formula _Al 2 _{O 3,} are widely encompassing concept of a material containing _Al 2 _{O 3,} in addition to _Al 2 _{O 3} Includes particles containing other inorganic compounds such as metal components. In addition to pure aluminum oxide, the alumina particles may contain salts and composite oxides with Al and various other elements, or may contain hydrated oxides such as hydroxides. The alumina in the silica particles and / or the alumina particles may be crystalline, amorphous, or a mixture thereof. This is preferable because the heat transfer by is small and the heat insulation performance is high.

Specific examples of the silica particles include the following.
An oxide of silicon called “silica” or “quartz”.
Partial oxide of silicon.
Silicon complex oxide such as silica alumina and zeolite.
Any one of silicate (glass) of Na, Ca, K, Mg, Ba, Ce, B, Fe and Al.
A mixture of an oxide, partial oxide, salt or composite oxide (alumina, titania, etc.) of an element other than silicon and an oxide, partial oxide, salt or composite oxide of silicon.
SiC and SiN oxides.

Specific examples of the alumina particles include the following.
An oxide of aluminum called “alumina”.
Alumina called α-alumina, γ-alumina, β-alumina.
Partial oxide of aluminum.
Aluminum complex oxides such as silica alumina and zeolite.
Any one of Na, Ca, K, Mg, Ba, Ce, B, Fe and Si aluminate (glass).
A mixture of an oxide, partial oxide, salt or composite oxide (such as silica or titania) of an element other than aluminum and an oxide, partial oxide, salt or composite oxide of aluminum.
An oxide of aluminum carbide or aluminum nitride.

It is preferable that the silica particles and / or alumina particles are thermally stable at the temperature at which the heat insulating material is used. Specifically, it is preferable that the weight of silica particles and / or alumina particles does not decrease by 10% or more when held for 1 hour at the maximum use temperature of the heat insulating material. Moreover, it is preferable that a silica particle and / or an alumina particle have water resistance from a viewpoint of maintaining heat insulation performance and a viewpoint of the shape maintenance at the time of shape | molding. Specifically, the amount of silica particles and / or alumina particles dissolved in 100 g of water at 25 ° C. is preferably less than 0.1 g, and more preferably less than 0.01 g.

The specific gravity of the silica particles and alumina particles is preferably 2.0 or more and 5.0 or less. It is more preferable that it is 2.0 or more and 4.5 or less because the bulk density of the heat insulating material is small, and it is further more preferable that it is 2.0 or more and 4.2 or less. Here, the specific gravity of silica particles and alumina particles refers to the true specific gravity determined by the pycnometer method.

As described above, it is known that a porous body having voids with a diameter of 100 nm or less has a low thermal conductivity and is suitable for a heat insulating material. When it is desired to obtain such a heat insulating material, it is simple to form fine particles having a particle diameter of 100 nm or less by pressing or the like. The following void diameter 100nm are formed in the green body, in order to facilitate indicates thermal insulation, or less 30nm particle diameter D _S 5 nm or more "small particles".

However, when a porous body is produced by, for example, pressure molding using a powder consisting only of so-called ultrafine particles having a particle diameter of about 20 nm, the volume of the powder before pressing tends to be very large, The manufacturing equipment tends to be large, and the stroke during pressurization becomes longer. As a result, the tact time, that is, the powder is filled into the mold, pressed, the pressure is released, and the powder is pressed from the mold. In addition to taking a long time to take out the molded body, there is a tendency that lamination tends to occur and the defect rate is high, so that productivity tends to decrease. Further, since the bulk density is small, it tends to be difficult to uniformly fill the mold. Furthermore, for example, in the powder supply process, scattering when the storage hopper is charged and aggregation within the storage hopper are likely to occur, and molding defects are likely to occur during pressure molding. In order to suppress molding defects, for example, when the amount of ultrafine particles is reduced and the amount of inorganic fibers is increased, the heat insulation performance is deteriorated as the use as a heat insulating material is impaired.

However, surprisingly, even if particles (large particles), such as micrometer-order particles with a small particle size (large particles), which were conventionally regarded as unsuitable as a heat insulating material, are used, the amount of ultrafine particles is surprisingly appropriate. It was found that by mixing with (small particles), a heat insulating material capable of achieving both compressive strength and excellent heat insulating performance can be obtained.

If the amount of the thermal conductivity is below 0.05 W / m · K of thermal insulation material, the content of the following small particles 30nm or 5nm particle diameter D _S is not particularly limited, the present inventors have investigated However, in addition to the small particles, as the large particles, a particle containing silica and / or alumina and having a particle diameter _DL of 50 nm or more and 100 μm or less is selected, and the large particles with respect to the sum of the mass of the small particles and the mass of the large particles is selected. By mixing so that the ratio _RL of the mass of particles is in the range of 60% by mass or more and 90% by mass or less, the volume of the powder before pressurization does not become too large, and it is easy to fill the mold. It has been found that powders that are difficult to scatter and aggregate can be obtained.

Further the present inventors have repeated studies, loose packing bulk density of small particles and large particles were mixed powdery thermal insulator, said at R _L range of 0 to less than 60% by weight regardless of the R _L It was found that the loosely filled bulk density tends to be small, whereas when _RL is 60% by mass or more, the loosely filled bulk density of the powdery heat insulating material tends to increase (see FIG. 1). That is, when _RL is 60% by mass or more, it is estimated that the loosely packed bulk density of the powdery heat insulating material becomes an appropriate size, the volume before pressurization does not become too large, and the mold is easily filled. Is done. The reason is not clear, different filling state of small particles and large particles by R _L, since the gap R _L is less than 60% by weight formed by the small particles and the large particles are relatively large, powdery It is thought that the loosely packed bulk density of the heat insulating material becomes small. On the other hand, when _RL is 60% by mass or more, the packed state of small particles and large particles becomes denser, voids are reduced, and the loosely packed bulk density of the powdery heat insulating material is increased. Presumed. On the other hand, even though the voids are decreased, excellent thermal conductivity is exhibited when the small and large particles are mixed in the range of _RL of 60% by mass or more and 90% by mass or less. However, it is speculated that the voids formed by these particles form a bottleneck for heat conduction in the space and the heat conduction in the space is easily suppressed. In addition, particles with different particle diameters are mixed, and adhesion, interparticle friction angle, which is the physical friction angle between particles, internal friction angle, which is the friction angle between layers inside the powder, charging property, etc. It is speculated that it has become possible to alleviate problems such as the ease of scattering and agglomeration of a heat insulating material consisting only of fine particles.

In addition, as described later, as one of the methods for producing the heat insulating material of the present embodiment, a process of heating a raw material powder (inorganic mixture) while being pressure-molded, or heating after pressure-molding is performed. There are techniques to include. If the heat insulating material contains particles having different particle diameters, for example, small particles and large particles, depending on the heating temperature, there is a tendency that heat shrinkage is less likely to occur when heated compared to heat insulating materials mainly composed of small particles. is there. The reason for this is not clear, but is estimated as follows. When the heat insulating material is heated, the particles and inorganic fibers constituting the heat insulating material and the surfaces thereof are softened and melted, and the particles constituting the heat insulating material and the particles and inorganic fibers are fused to be strong. It is presumed that a simple joint is formed. As a result, it is estimated that the heat insulating material hardens and exhibits excellent compressive strength. At this time, if the heat insulating material contains large particles, joints are formed at the interfaces between the particles or between the particles and the inorganic fibers, but the particle size of the large particles themselves is kept approximately the same as before heating. Therefore, it is presumed that the heat shrinkage is small compared to the case where the main component of the heat insulating material is small particles, and at the same time, a state in which pores are present in the heat insulating material can be formed. For this reason, it is speculated that it is possible to achieve both heat insulation performance and compressive strength even if large particles with larger heat transfer due to solid conduction are included than small particles. If the heat shrinkage due to heating is large, the loss of the heat insulating material after heating with respect to the heat insulating material before heating, that is, the heat insulating material of the product becomes large.

That is, the heat insulating material preferably contains two or more kinds of silica particles and / or alumina particles, and particularly when two kinds of particles having different particle diameters, that is, small particles and large particles made of silica and / or alumina, The mass ratio _RL of the large particles is preferably 60% by mass or more and 90% by mass or less based on the sum of the mass of the small particles and the mass of the large particles. When the content ratio of the large particles is less than 60% by mass, the powder tends to be scattered, and when it exceeds 90% by mass, the heat insulating performance tends to be lowered and pressure molding tends to be difficult. The content ratio of large particles is more preferably 60% by mass or more and 85% by mass or less, and further preferably 65% by mass or more and 85% by mass or less from the viewpoint of heat insulation performance.

In addition, the New Energy and Industrial Technology Development Organization, 2005-2006 results report, Strategic development of energy use rationalization technology, practical development of energy use rationalization technology, “Development of ultra-low thermal conductive materials with nanoporous and composite structures” As described in “Practical development” (hereinafter referred to as “Non-patent document 3”), the heat-insulating material precursor mainly composed of ultrafine particles is molded when the pressure is released after pressure molding. The body tends to be large and easy to swell. This expansion is called springback. Like the silica molded body described in Patent Document 1, a molded body obtained by pressure-molding ultrafine particles containing ultrafine powder as a main component has a problem that a springback occurs and a molding defect occurs in some cases. . Certainly, the microporous structure contributes to reducing the heat conduction of the heat insulating material, but spring back is likely to occur if the air is not sufficiently vented during pressure molding. By blending large particles, the occurrence of springback during molding tends to be suppressed as compared to the case consisting of only small particles, but the suppression effect is significant when the blending ratio is 25% by mass or more. . As described above, since the heat insulation performance tends to be lowered when the mixing ratio of the large particles is too large, the ratio of the large particles to the small particles of the heat insulating material is the scatterability of the powder used as the raw material of the heat insulating material. It is preferable to determine the balance so that the spring back suppression and the thermal conductivity of the heat insulating material become desired values.

In the heat insulating material described in Patent Document 2, as disclosed in Non-Patent Document 3, a crack-shaped molding defect occurs on a surface perpendicular to the press surface during pressure molding. If such a molding defect exists in the heat insulating material, the heat insulating material may be damaged, and the heat insulating performance is also deteriorated, so that it cannot be handled as a product and the yield is reduced, which is not preferable. Further, a heat insulating material mainly composed of ultrafine particles also tends to cause lamination after being pressure-molded. Lamination refers to a phenomenon in which a molded product obtained by pressure molding is peeled into two or more layers mainly in the thickness direction. If such delamination occurs, it cannot be handled as a product, and the yield decreases, which is not preferable. Large particles and small particles mainly composed of silica, where the average value of the large particles is 50 nm to 10 μm, and the average value of the small particles is 5 nm to 30 nm, If the ratio is preferable for the above-described springback suppression, lamination tends to be difficult to occur. As described above, when the mixing ratio of the large particles is 60% by mass or more, the loosely packed bulk density becomes an appropriate size and the stroke is reduced, and the average particle diameter of the large particles and the small particles is within the above range. If so, the packed state of particles becomes a preferable mode, and the effect of suppressing lamination tends to be remarkable. Use of such a powder as a raw material for the heat insulating material of the present embodiment is very suitable in that the defect rate of the heat insulating material is low and the productivity is improved.

The loosely packed bulk density of the powder (inorganic mixture) used as the raw material for the heat insulating material is preferably 0.030 g / cm ³ or more and 0.35 g / cm ³ or less. When the loosely packed bulk density is less than 0.030 g / cm ³ , the volume of the heat insulating material is large, and, for example, a device necessary for pressure molding tends to increase in size, and it tends to remarkably scatter and aggregate. Therefore, it is not preferable. If the loosely packed bulk density is more than 0.35 g / cm ³ , the heat insulation performance tends to be lowered, which is not preferable. Before pressing the appropriate size Satoshi volume, more preferably 0.035 g / cm ³ or more 0.3 g / cm ³ or less from the viewpoint of facilitating the filling of the mold, 0.040 g / cm in terms of thermal insulation performance ³ to 0.25 g / cm ³ or less is more preferred. In addition, when the heat-insulating material contains infrared opaque particles, there is a strong tendency to require heat insulation performance at a high temperature, so that the volume before pressurization is appropriately sized and the mold can be easily filled. from the viewpoint of heat insulating performance at high temperature range, loose packing bulk density is preferably 0.045 g / cm ³ or more 0.25 g / cm ³ or less, and more is 0.05 g / cm ³ or more 0.25 g / cm ³ or less preferably, further preferably 0.05 g / cm ³ or more 0.20 g / cm ³ or less. Details of the infrared opaque particles will be described later.

In the present specification, the “loosely packed bulk density” refers to a value obtained according to the measurement procedure of “initial bulk density” of JIS R 1628. Specifically, in “7.1 Procedure for Constant Volume Measurement”, (1) to (4), that is,
(1) The mass of the measurement container is measured with a scale.
(2) Place the sample in the measuring container until it overflows through the sieve. At this time, the measurement container should not be vibrated or the sample should not be compressed.
(3) Grind the powder that has risen from the upper end surface of the measurement container using a grinding plate. At this time, the ground plate is used by being inclined backward from the direction of grinding so as not to compress the powder.
(4) The entire measurement container is weighed with a scale, and the mass of the sample is calculated by subtracting the weight of the measurement container.
Measure based on JIS R 1628 is an index based on the premise that the difference between the initial bulk density and the bulk density of this measurement is within 0.3%, whereas in the case of the powdery heat insulating material of this embodiment, the initial The difference between the bulk density and the original bulk density may be greatly different. However, the present inventor has found that the initial bulk density is an important indicator for the ease of lamination when pressure-forming a powdery heat insulating material. Completed the invention. An example of an apparatus for measuring loosely packed bulk density is shown in FIG. The distance between the tip of the funnel attached to the lower part of the sieve and the measuring container shall be 20-30 mm.

The content of small particles and large particles can be calculated, for example, by separating small particles and large particles from the heat insulating material and measuring their masses. The method for separating the small particles and the large particles is not particularly limited. For example, the particles can be separated using a classification method or a classification machine described in the revised sixth edition, Chemical Engineering Handbook (Maruzen). Known classification methods include wet classification and dry classification. Wet classification machines include gravity classifiers (sediment classifiers), spitz casters, hydraulic classifiers, siphon sizers, centrifugal classifiers, liquid cyclones, jet sizers, rake classifiers, Aikens types, spiral classifiers, bowl classifiers. Machine, hydro separator, decanter and the like. Machines for dry classification include sieving machines such as vibrating screens, in-plane screens, rotary screens, double cylinder type screens, gravity classifiers, zigzag classifiers, wind classifiers, free vortex type centrifugal classifiers, cyclones, Perfusion separator, forced vortex type centrifugal classifier, turbo classifier, microplex, micron separator, Accucut, super separator, startervant type classifier, turboplex, cyclone air separator, centrifugal classifier such as O-SEPA, louver type classifier And inertia classifiers such as a fanton gelen classifier, elbow jet, and improved virtual impactor. The classifier may be selected according to the particle size of small particles and large particles to be separated, and these classifiers may be used in combination.

The particle diameter of the silica particles and alumina particles can be measured by observing the cross section of the heat insulating material with a field emission scanning electron microscope (FE-SEM). When measuring the particle size of small particles, set the magnification so that particles of 5 nm or more and 30 nm or less can be observed (for example, 10000 times), and randomly extract “representative cross-sectional field of view” for the thermal insulation. To do. “Representative cross-sectional field of view” means a field of view in which the state of the cross-sectional shape is common to some extent in arbitrarily selected cross-sections, not a specific surface in the cross-section of the heat insulating material. For example, if there is unevenness of particles in the thickness direction of the heat insulating material in a large number of cross sections, a typical sectional view of the heat insulating material including the presence of the unevenness is formed. Should be selected in a balanced manner. On the other hand, in the case of a heat insulating material containing particles or fibers far larger than small particles, there may be a field of view that is occupied by most of them, but the field of view observed only in a very small section is Since this is not a representative field of view, this is not selected. In the case of observing at a magnification of 10,000 times, first, observing at about 100 times, selecting an average field of view, and observing at a magnification of 10000 times is a preferable embodiment from the viewpoint of little time loss.

If a typical cross-sectional visual field is observed, and two or more small particles are observed in the visual field, it can be determined that the heat insulating material is “contains small particles”. However, even when two or more small particles are not observed in the initially observed visual field, if a typical sectional visual field is observed in 100 visual fields and a total of 100 small particles can be observed, “contain small particles”. And That is, in this specification, (1) if two or more small particles are observed in the typical cross-sectional field observed at the beginning, “contains small particles” is satisfied, and (2) observed at the beginning. If two or more small particles are not observed in the representative cross-sectional field of view, if a total of 100 small particles are observed in the representative cross-sectional field of view of 100, "contains small particles" is satisfied. Then define.

The particles do not necessarily have to be circular particles, and may have an irregular shape. The diameter of the particles is determined by the equivalent area equivalent circle diameter. The equivalent area equivalent circle diameter is the diameter of a circle having the same area as the projected area of the particles, and is also called the Heywood diameter. Even if there are irregularly shaped particles, if the area is 78 nm ² (corresponding to the area of a circle having a particle diameter of 10 nm), the particle diameter is considered to be 10 nm. If insulation comprising heating in the manufacturing process, small particles with each other and fused, the boundary may sometimes invisible, the fusion was distorted cross-sectional area in the shape 702nm 2 ⁽⁼ circle particle diameter of 30nm If it is less than or equal to the area, it is understood as one “small particle”. Even if a certain degree of fusion has occurred, the particle diameter (equivalent area equivalent circle diameter) of each particle may be measured as long as the boundary can be visually recognized at that magnification.

In determining whether or not to include small particles, the particle size of each particle may be determined by the equivalent area circle equivalent diameter, so it is not essential to determine the average value of the particle size, but the entire set of small particles If the average value of the particle diameter is determined for the purpose of grasping the tendency of the physical properties of the heat insulating material, the magnification is set so that particles of 5 nm to 30 nm can be observed, and 100 or more particles are observed. What is necessary is just to calculate | require by a number average by calculating | requiring an equal area equivalent circle diameter.

The cross section of the heat insulating material can be observed with the following conditions and apparatus, for example. Using a cross section polisher (SM-09010, manufactured by JEOL Ltd.), BIB (broad ion beam) processing was applied to the insulation material as a sample under the conditions of acceleration voltage 4.0 kV and processing time 9 hours, obtain. This sample is loaded on a sample stage and Os coating of about 2 nm is applied to prepare a sample for speculum. The Os coating can be applied using, for example, an osmium coater (HPC-1SW type, manufactured by Vacuum Device Corporation). As a speculum, a scanning electron microscope (S-4700, manufactured by Hitachi, Ltd.) is used, and measurement is performed under the condition of an acceleration voltage of 1.0 kV.

Particle diameter _{D S} of the small particles is preferably 5nm or more 30nm or less. If D _S is in 5nm or more, compared to the case D _S is outside the above numerical range, they tend small particles are chemically stable, heat-insulating performance may stable tendency. If D _S is a 30nm or less, compared with the case D _S is outside the above numerical range, small contact area between the small particles, less heat transfer due to the powder of the solid conduction, tends low thermal conductivity There is. D _S is, if it is 5nm or 25nm or less, from the viewpoint of thermal conductivity, more preferable to be 5nm or more 20nm or less, more preferable to be 5nm or more 18nm or less, and particularly preferably 7nm more 14nm or less.

The particle diameter D _L of the large particles satisfies D _S <D _L. D _L is preferably at 50nm or more 100μm or less. D _L is obtained by the same method as D _S described above. When _DL is 50 nm or more, when the heat insulating material is molded, the spring back in the molded product tends to be small. When _DL is 100 μm or less, the thermal conductivity tends to be small. Particle diameter D _L of the larger particles, if it is 50nm or more 50μm or less, because heat insulating material is easy uniform mixing thereof with the case containing the inorganic fibers and the infrared opacifying particles, preferably. D _L is, if it is 50nm or more 10μm or less, increase adhesion of the particles, for separation of particles from the powder is small, and still more preferably 50nm or more 5μm or less.

When D _L is at least twice the D _S, since the spring-back is reduced in the case of molding the heat insulator, preferred. D _L is the is more than three times D _S, large bulk density of the mixed powder of small particles and large particles, because of their high workability powder volume is small, more preferred. D _L is the is more than 4 times the D _S, large difference in particle size of the small particles and large particles, since it is easy to disperse for small particles of large particles when mixed with small particles and large particles, further preferable. From the viewpoint of solid heat transfer due to particle aggregation, it is preferable that each particle is dispersed. That is, it is preferable that there are no locations where large particles are in direct contact with each other and connected. The voids between the large particles generated when the large particles are not directly connected are filled with small particles, and the large particles are difficult to directly contact each other. Therefore, there is no heat transfer path with large solid conduction in the heat insulating material, and the heat conductivity of the whole heat insulating material tends to be low. Furthermore, by filling the gaps between the large particles with small particles, the size of the gaps present in the heat insulating material is reduced, and air convection and heat transfer are suppressed, so the thermal conductivity of the entire heat insulating material is reduced. It tends to be low.

The heat insulating material preferably contains a water repellent from the viewpoint of suppressing deterioration of handling properties, deformation of the heat insulating material, cracking, and the like when water is immersed in the heat insulating material. Examples of the water repellent include wax-based water repellents such as paraffin wax, polyethylene wax, and acrylic / ethylene copolymer wax; silicon-based water repellents such as silicon resin, polydimethylsiloxane, and alkylalkoxysilane; Fluorine-based water repellents such as carboxylates, perfluoroalkyl phosphate esters and perfluoroalkyltrimethylammonium salts, silane coupling agents such as alkoxysilanes containing alkyl groups and perfluoro groups, trimethylsilyl chloride and 1,1,1 And silylating agents such as 3,3,3-hexamethyldisilazane. These can be used alone or in combination of two or more. These may be used as they are, or in the form of a solution or an emulsion. It is also possible to apply the water repellent as it is or in the form of a solution or an emulsion to the heat insulating material. Although the method of apply | coating is not specifically limited, For example, brush coating, roller coating, spraying, spraying, airless spray, roll coater, and immersion are mentioned. A water-repellent effect can also be obtained when a water-repellent agent is added to a powder that is a raw material of a heat-insulating material and a heat-insulating material is produced using a powder subjected to water-repellent treatment. The method of adding the water repellent to the powder is not particularly limited. For example, a method in which the powder is stirred and dried while adding a solution obtained by diluting these water repellents with a solvent such as water or alcohol. Examples include a method of dispersing in a solvent such as water or alcohol to form a slurry, adding a water repellent thereto, stirring and filtering, and drying, and steaming with chlorotrimethylsilane. Of these, wax-based water repellents and silicon-based water repellents are preferably used in the present embodiment. The content of the water repellent in the inorganic mixture is preferably 100/30 to 100 / 0.1 in terms of the mass of the whole inorganic mixture / the mass of the water repellent from the viewpoint of imparting a sufficient water repellent effect. 20 to 100 / 0.5 is more preferable, and 100/10 to 100/1 is more preferable.

[1-2] Inorganic fiber The heat insulating material preferably contains inorganic fiber from the viewpoint of ease of molding. The heat insulating material containing inorganic fibers has an advantage that, in pressure molding, there is little dropout of particles from the formed heat insulating material, and the productivity is high. Furthermore, the heat insulating material containing an inorganic fiber has the advantage that it is hard to disintegrate and is easy to handle. Even in the state of powder as a raw material of the heat insulating material, it is preferable in handling because it is less scattered. In the present specification, the term “inorganic fiber” means that the ratio of the average length of the inorganic fiber to the average thickness (aspect ratio) is 10 or more. The aspect ratio is preferably 10 or more, and when molding a heat insulating material, 50 or more is more preferable from the viewpoint of enabling molding with a small pressure and improving the productivity of the heat insulating material, from the viewpoint of the bending strength of the heat insulating material. 100 or more is more preferable. The aspect ratio of the inorganic fiber can be obtained from the average value of the thickness and length of 1000 inorganic fibers measured by FE-SEM. It is preferable that the inorganic fibers are monodispersed and mixed in the powder, but the inorganic fibers may be mixed in a state in which the inorganic fibers are entangled with each other or a bundle in which a plurality of inorganic fibers are aligned in the same direction. . In the monodispersed state, the inorganic fibers may be aligned in the same direction. However, from the viewpoint of reducing the thermal conductivity, the inorganic fibers are oriented in a direction perpendicular to the heat transfer direction. It is preferable. The method for orienting the inorganic fibers perpendicularly to the heat transfer direction is not particularly limited.For example, when filling the mold with the powder as the raw material of the heat insulating material, the powder is dropped from a high place to the filling point. By filling, the inorganic fibers tend to be oriented perpendicular to the heat transfer direction. In the case of pressure molding, for example, by pressing in the same direction as the heat transfer direction, the inorganic fibers that have been oriented in the heat transfer direction can be easily oriented in a direction perpendicular to the heat transfer direction.

Examples of inorganic fibers include long glass fibers (filaments) (SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ —CaO), glass fibers, glass wool (SiO ₂ —Al ₂ O ₃ —CaO—Na ₂ O). Alkali resistant glass fiber (SiO ₂ —ZrO ₂ —CaO—Na ₂ O), rock wool (basalt wool) (SiO ₂ —Al ₂ O ₃ —Fe ₂ O ₃ —MgO—CaO), slag wool (SiO ₂ —) Al ₂ O ₃ —MgO—CaO), ceramic fiber (mullite fiber) (Al ₂ O ₃ —SiO ₂ ), silica fiber (SiO ₂ ), alumina fiber (Al ₂ O ₃ —SiO ₂ ), potassium titanate fiber, Alumina whisker, silicon carbide whisker, silicon nitride whisker, calcium carbonate whisker, basic magnesium sulfate whisker Car, calcium sulfate whisker (gypsum fiber), zinc oxide whisker, zirconia fiber, carbon fiber, graphite whisker, phosphate fibers, AES (Alkaline Earth Silicate) fiber _(SiO 2 -CaO-MgO), natural mineral wollastonite, Sepiolite, attapulgite, and blue sight.

Among inorganic fibers, it is preferable to use biosoluble AES fibers (Alkaline Earth Silicate Fiber) that are safe for the human body. Examples of the AES fiber include SiO ₂ —CaO—MgO inorganic glass (inorganic polymer).

The average thickness of the inorganic fibers is preferably 1 μm or more from the viewpoint of preventing scattering. In the case of a heat insulating material, the thickness is preferably 20 μm or less from the viewpoint of suppressing heat transfer by solid conduction. The average thickness of the inorganic fibers can be obtained by calculating the thickness of 1000 inorganic fibers by FE-SEM and averaging the thicknesses.

The content of the inorganic fibers in the heat insulating material is preferably more than 0% by mass with respect to the total mass of the heat insulating material from the viewpoint of suppressing the detachment of the powder, and the heat conductivity is 0.05 W / m · K or less. It is preferable that it is 20 mass% or less.

When the heat insulating material contains the infrared opaque particles, the content of the inorganic fiber is more preferably 0.5% by mass or more and 18% by mass or less from the viewpoint of easy mixing with the infrared opaque particles. From the viewpoint of reducing the loosely packed bulk density of the powder as the raw material of the material, it is more preferably 0.5% by mass or more and 16% by mass or less.

The content of the inorganic fiber can be obtained, for example, by classification from a powder using the inorganic fiber as a raw material for the heat insulating material.

[1-3] Infrared opacifying particles It is preferable that the heat insulating material contains infrared opacifying particles when heat insulating performance at a high temperature is required. The infrared opaque particles refer to particles made of a material that reflects, scatters, or absorbs infrared rays. When infrared opaque particles are mixed in the heat insulating material, heat transfer due to radiation is suppressed, so that the heat insulating performance is particularly high in a high temperature region of 200 ° C. or higher.

Examples of infrared opaque particles include zirconium oxide, zirconium silicate, titanium dioxide, iron titanium oxide, iron oxide, copper oxide, silicon carbide, gold ore, chromium dioxide, manganese dioxide, graphite and other carbonaceous materials, carbon fibers , Spinel pigments, aluminum particles, stainless steel particles, bronze particles, copper / zinc alloy particles, and copper / chromium alloy particles. Conventionally, the above metal particles or nonmetal particles known as infrared opaque materials may be used alone or in combination of two or more.

As the infrared opaque particles, zirconium oxide, zirconium silicate, titanium dioxide or silicon carbide is particularly preferable. The composition of the infrared opaque particles is obtained by FE-SEM EDX.

The average particle diameter of the infrared opaque particles is preferably 0.5 μm or more from the viewpoint of heat insulation performance at 200 ° C. or more, and preferably 30 μm or less from the viewpoint of heat insulation performance at less than 200 ° C. due to suppression of solid conduction. The average particle diameter of the infrared opaque particles is determined by the same method as that for silica particles and alumina particles. Depending on the size of the inorganic fibers, silica particles, and alumina particles, when the silica particles and / or alumina particles are 5 nm to 100 μm, the infrared opaque particles can be used from the viewpoint of easy mixing with the silica particles and / or alumina particles. The average particle size is more preferably from 0.5 μm to 10 μm, and even more preferably from 0.5 μm to 5 μm.

The content of the infrared opaque particles in the heat insulating material is preferably 0.1% by mass or more and 39.5% by mass or less. If the content of the infrared opaque particles is larger than 39.5% by mass, heat transfer by solid conduction is large, so that the heat insulation performance at less than 200 ° C. tends to be low. In order to improve the heat insulation performance at 200 ° C. or higher, the content of the infrared opaque particles is more preferably 0.5% by mass to 35% by mass, and further preferably 1% by mass to 30% by mass. Further, when the content of the infrared opaque particles in the heat insulating material is within the above range, it tends to be more than 0% by volume and 5% by volume or less based on the volume of the whole heat insulating material. According to the studies by the inventors, the infrared reflection, scattering or absorption efficiency of the infrared opaque particles tends to depend on the volume ratio of the infrared opaque particles contained in the heat insulating material, and the infrared opaque particles in the heat insulating material. The content of is preferably more than 0% by volume and 5% by volume or less based on the volume of the whole heat insulating material. When the content of the infrared opaque particles is greater than 5% by volume, heat transfer by solid conduction is large, and thus the heat insulation performance at less than 200 ° C. tends to be low. In order to improve the heat insulation performance at 200 ° C. or higher, the content of the infrared opaque particles is more preferably 0.02% by volume or more and 5% by mass or less, and further preferably 0.03% by volume or more and 4% by volume or less. . Thermal insulation containing infrared opacifying particles tends to have a small thermal shrinkage, for example, when it is suddenly exposed to excessive heat, it has the effect of delaying the shape change or the thermal insulation collapse. is there. Insulating materials containing infrared opacifying particles tend to have less powder falling off the insulating material, the belt conveyor that transports the insulating material in the production line is less likely to get dirty, and hands are less likely to get dirty when holding the insulating material. In addition, there is an effect that the place where the heat insulating material comes into contact is hard to get dirty. If there is little powder fall off from the heat insulating material, for example, when a resin film is used as the covering material and the heat insulating material is vacuum-packed, there is an advantage that the powder hardly adheres to the sealing surface of the resin film and the workability is excellent.

The content of the infrared opaque particles can be determined, for example, by measuring the composition of the infrared opaque particles with FE-SEM EDX and quantifying the elements contained only in the infrared opaque particles by fluorescent X-ray analysis. it can.

[1-4] Compressive strength The heat insulating material of the present embodiment is unlikely to be collapsed or deformed during compression, can be shaped without cutting, and can be processed such as cutting. The maximum load in the range of ˜5% is preferably 0.7 MPa or more. The pressure is more preferably 2.0 MPa or more, further preferably 3.0 MPa or more, and particularly preferably 6.29 MPa or more. The upper limit of the maximum load in the range where the compression rate is 0 to 5% is not particularly limited, but 30 MPa or less is appropriate from the viewpoint of heat insulation performance.

The compression rate can be calculated from the sample thickness at the time of compressive strength measurement, that is, the stroke (push-in distance) with respect to the length of the sample in the compression direction. For example, when the compression strength is measured using a sample in which the molded body has a cubic shape of 1 cm × 1 cm × 1 cm, a state where the stroke is 0.5 mm is defined as a compression rate of 5%. The compression rate is calculated by the following mathematical formula (1).
Compression rate = 100 × stroke (push-in distance) / length in sample compression direction (1)

The pattern of the load-compressibility curve drawn when measuring the compressive strength is not particularly limited. That is, when the compression ratio is in the range of 0 to 5%, the molded body as a sample may collapse and show a clear breaking point, or may not collapse. When the compact as a sample collapses and exhibits a fracture point when the compression ratio is in the range of 0 to 5%, the maximum load of the compact is defined as the load at the fracture point. The load at the breaking point is preferably 0.7 MPa or more, more preferably 2.0 MPa or more, and further preferably 3.0 MPa or more. If the sample does not collapse, it is evaluated using the maximum load value indicated by the compression ratio in the range of 0-5%.

The compressive strength is measured according to JIS R1608. However, not all are in accordance with the standard, but the sample shape is as follows. The heat insulating material is processed to a length of 2 cm, a width of 2 cm, and a thickness of 2 cm, and measurement is performed without using a pressure plate. Although the standard requires accuracy of ± 0.1 mm, this level of accuracy is not necessarily required. Since the shape of the sample is changed, the compression strength is not calculated according to the standard, and is calculated from the measured value according to the following mathematical formula (2).
σ = F _max / A ₀ (2)

Here, σ is the compressive strength (MPa) of the heat insulating material used as a sample, F _max is the recorded maximum load (N), and A ₀ is the cross-sectional area (mm ² ) of the sample before measurement. When the compact as a sample collapses and exhibits a fracture point when the compression rate is in the range of 0 to 5%, that is, when F _max is obtained, the compressive strength is calculated according to the above formula (2). On the other hand, if the sample does not collapse, the maximum load value indicated by the compression rate in the range of 0 to 5%, that is, the load value at the compression rate of 5% is substituted for F _max in the above equation (2). Compressive strength.

As a measuring device, a precision universal testing machine, Autograph AG-100KN (manufactured by Shimadzu Corporation) is used, and the compressive strength is measured at an indentation speed of 0.5 mm / min as in JIS R1608.

[1-5] Thermal conductivity The thermal conductivity of this embodiment has a thermal conductivity at 30 ° C. of 0.05 W / m · K or less. From the viewpoint of heat insulation performance, the thermal conductivity is preferably 0.045 W / m · K or less, more preferably 0.040 W / m · K or less, still more preferably 0.037 W / m · K or less, and 0.0213 W / m. -K or less is particularly preferable. The heat insulating material containing the infrared opaque particles is preferable particularly when heat insulating performance in a high temperature region of 200 ° C. or higher is required. When the powder contains infrared opaque particles, the thermal conductivity at 800 ° C. is preferably 0.2 W / m · K or less, more preferably 0.19 W / m · K or less, and 0.18 W / m · K or less. Is more preferable. A method for measuring the thermal conductivity will be described later.

When preparing a heat insulating material by mixing a plurality of types of silica particles and / or alumina particles, for example, small particles and large particles, the heat insulating material may contain _RL in the range of 60% by mass to 90% by mass. It is preferable to measure the thermal conductivity after preparing. When the thermal conductivity is more than 0.05 W / m · K, it is preferable to change the mixing amount within a range in which the content rate is maintained. The mixing amount can be similarly determined when using inorganic fibers and infrared opaque particles. If the mixing amount of the inorganic fiber and the infrared opaque particles is excessive, the heat insulating property may be lowered. Therefore, it is preferable to appropriately prepare while measuring and confirming the thermal conductivity. For example, when inorganic fibers having an average fiber diameter of 12 μm and an average length of 5 mm are mixed with silica, the mixing ratio of the inorganic fibers is preferably 18% by mass or less. For example, when mixing infrared opaque particles having an average particle diameter of 2 μm with silica, the mixing ratio of infrared opaque particles is preferably 23% by mass or less. Further, when inorganic fibers or infrared opaque particles made of a material having a low thermal conductivity are selected, a mixed powder having a thermal conductivity of 0.05 W / m · K or less tends to be easily prepared.

[1-6] Bulk Density The bulk density of the heat insulating material of the present embodiment is preferably 0.2 g / cm ³ or more and 1.5 g / cm ³ or less. If the bulk density of the heat insulating material is smaller than 0.2 g / cm ³ , the compressive strength of the heat insulating material tends to decrease. If the bulk density of the heat insulating material is larger than 1.5 g / cm ³ , the heat insulating performance tends to be reduced, and the burden when the heat insulating material is transported increases. From the viewpoint of achieving both compressive strength and heat insulation performance and from the viewpoint of reducing the burden when transporting the heat insulating material, 0.25 g / cm ³ or more and 1.2 g / cm ³ or less is more preferable, and 0.30 g / cm ³ or more and 1 More preferably, it is 0.0 g / cm ³ or less. Here, the bulk density is defined by measuring and calculating the size and mass of the heat insulating material in a form in which the heat insulating material is actually used. For example, in the case where the heat insulating material has a layer structure, the bulk density of only the specific layer is not measured, but the dimensions and mass are measured in the form actually used, that is, in the state of the layer structure. If the bulk density does not change due to processing such as cutting, it is possible to measure the bulk density by making the heat insulating material easy to measure. The mass of the heat insulating material is measured at normal temperature and normal pressure. That is, measurement is performed including the air that the heat insulating material has in its pores. The volume of the heat insulating material is calculated based on the outer dimensions. That is, it is set as the volume of a heat insulating material also including the pore volume of a heat insulating material. When the mass of the heat insulating material measured by the method described above is P [g] and the volume is Q [cm ³ ], the bulk density of the heat insulating material is P ÷ Q = P / Q [g / cm ³ ].

[1-7] Pore Volume In the heat insulating material of the present embodiment, the pore volume is preferably 0.5 mL / g or more and 2 mL / g or less. Here, the pore volume is defined by a value measured by a mercury intrusion method to be described later, and means an integrated pore volume V _0.003 of pores having a pore diameter of 0.003 μm to 150 μm. When the pore volume is larger than 2 mL / g, the compressive strength of the heat insulating material tends to decrease, and when the pore volume is less than 0.5 mL / g, the heat insulating performance tends to decrease. A pore volume of 0.5 mL / g or more and 2 mL / g or less means that the heat insulating material has pores. When the pore volume is within this range, it is estimated that appropriate pores exist in the heat insulating material, heat transfer due to solid conduction is suppressed, and excellent heat insulating performance can be exhibited. On the other hand, it is estimated that the strength that can suppress the compressive deformation is expressed by the pore volume of the heat insulating material not being too large. Moreover, when the pore volume is within this range, the above-described bulk density range tends to be easily achieved. From the viewpoint of achieving both compressive strength and heat insulation performance, the pore volume is more preferably 0.8 mL / g or more and 1.8 mL / g or less, and further preferably 0.8 mL / g or more and 1.6 mL / g or less.

[1-8] Ratio of accumulated pore volume In the heat insulating material of this embodiment, the ratio R of the accumulated pore volume V of pores having a pore diameter of 0.05 μm to 0.5 μm is 0. It is preferable that it is 70% or more with respect to the cumulative pore volume V _{0.003 of the} pores which are 003 μm or more and 150 μm or less. When R is in this range, the compressive strength of the heat insulating material tends to increase, and when it gets wet with water (liquid), it tends not to collapse into powder. R may be expressed as (V / V _0.003 ) × 100. It means that the larger R is, the narrower the pore distribution is, and the pore diameter is in the range of 0.05 μm to 0.5 μm. It is presumed that the structure of the heat insulating material is made uniform and the excellent compressive strength is expressed by the more uniform pore diameter. The pore distribution of the heat insulating material with R of less than 70% is as follows: (1) When there are many pores with a pore diameter of less than 0.05 μm, (2) Fine pores with a pore diameter of more than 0.5 μm. When there are a large number of pores, (3) it is assumed that there are pores having a pore diameter of less than 0.05 μm and more than 0.5 μm, respectively, and there are few pores of 0.05 μm or more and 0.5 μm or less. In the case of (1), when the heat insulating material gets wet with water (liquid), it tends to collapse into a powder form. In the case of (2), the heat insulating performance tends to be low. In the case of (3), The tendency of (1) and (2) appears according to the ratio of the pore diameter. The reason for this is not clear, but in the case of (1), when it gets wet, a shrinkage force is generated by capillary action, and the particles forming the voids move and the heat insulating material is distorted, resulting in a powdery state. It is estimated that it will easily collapse. In the case of (2), since the pore diameter is larger than about 100 nm, which is the mean free path of air molecules, heat transfer due to air convection and conduction is hardly suppressed, and it is estimated that the heat insulation performance is lowered. R is more preferably 75% or more and further preferably 80% or more with respect to the total pore volume of the heat insulating material. The upper limit of R is 100%.

[1-9] Content of Alkali Metal Element, Alkaline Earth Metal Element, Ge, P, Fe From the viewpoint of sufficiently curing the heat insulating material and increasing the compressive strength, the powder of the present embodiment comprises an alkali metal element, It is preferable to include at least one element selected from the group consisting of an alkaline earth metal element and germanium. Specific examples of at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements (hereinafter sometimes referred to as “basic elements” in the present specification) include lithium, sodium, potassium, Examples thereof include alkali metals such as rubidium and cesium, and alkaline earth metals such as magnesium, calcium, strontium and barium. Only one basic element may be included, or two or more basic elements may be included. Although the kind is not specifically limited, Sodium, potassium, magnesium, and calcium are preferable at the point which can be hardened by comparatively low-temperature heat processing, when improving the adhesiveness of particle | grains and heat-processing.

When heat treatment is performed on the heat insulating material, in the heat treatment step, the heat insulating material contains basic element or Ge, so that the basic element melts or is a main component of the heat insulating material such as silica or alumina. The inventor presumes that the melting point of the metal contributes to the curing of the heat insulating material by lowering the melting point. In the case of silica particles, it is considered that the silica particles are fused to each other at the particle interface, and a bond such as Si—O—Si is generated to form a strong joint. Si and Ge are elements belonging to the periodic table, and the oxides are tetravalent, such as SiO ₂ and GeO ₂ , respectively, so that they are easily incorporated into the crystal structure and form a strong structure. it is conceivable that. It is considered that the formation of such strong joints and structures acts to stabilize the structure formed by silica particles or alumina particles, and as a result, the heat insulating material as a whole is cured and the compressive strength is improved. Further, it is presumed that P and Fe also have the above-described action.

When the heat insulating material contains a basic element, the content of the basic element is preferably 0.005% by mass or more and 5% by mass or less based on the total mass of the heat insulating material. Is preferably 10 mass ppm or more and 1000 mass ppm or less, and the P content is preferably 0.002 mass% or more and 6 mass% or less.

The content of Fe is preferably 0.005% by mass or more and 6% by mass or less. Moreover, it is preferable that the content rate of P is 0.002 mass% or more and 6 mass% or less. Further, the basic element content is 0.005 mass% to 3 mass%, the Ge content is 20 mass ppm to 900 mass ppm, and the P content is 0.002 mass% to 5.5 mass%. Hereinafter, the Fe content is preferably 0.005 mass% or more and 3 mass% or less from the viewpoint of improving adhesion between particles and fluidity and suppressing aggregation. Furthermore, the basic element content is 0.005 mass% to 2 mass%, the Ge content is 20 mass ppm to 800 mass ppm, the P content is 0.002 mass% to 5 mass%, More preferably, the Fe content is 0.005 mass% or more and 2 mass% or less. The content of the basic elements, Ge, P, and Fe in the heat insulating material can be quantified by XRF (fluorescence X-ray analysis).

When alkali metal elements, alkaline earth metal elements, and Ge are contained in large particles, the dispersion and aggregation of powder, which is a raw material of the heat insulating material, is suppressed, and both heat insulating performance and compressive strength are compatible, and heat treatment is performed. This is preferable because the effect of improving the productivity tends to appear more remarkably. When heat treatment is performed, if the alkali metal element, alkaline earth metal element, and Ge are contained in the large particles, the specific surface area of the large particles is smaller than the specific surface area of the small particles. It is considered that it is possible to reduce the thermal conductivity of the entire molded body by not forming an unnecessarily large fused surface at the interface of the material and not having a heat transfer path with a large solid conduction in the heat insulating material. . The content of the basic elements and Ge, P, and Fe contained in the large particles can be determined, for example, by separating the small particles from the large particles by the above-described method and measuring by the fluorescent X-ray analysis method.

[2] Manufacturing method of heat insulating material The manufacturing method of the heat insulating material of the present embodiment accommodates an inorganic mixture containing small particles containing silica and / or alumina and having an average particle diameter of 5 nm to 30 nm in a mold. A housing step and a molding step for molding the inorganic mixture, wherein the molding step includes (a) a step of heating the inorganic mixture to 400 ° C. or higher while pressurizing the inorganic mixture with a mold, or (b) an inorganic mixture by pressurization. After the molding, a step of performing a heat treatment at a temperature of 400 ° C. or higher is included.

The average particle size of the small particles is preferably 5 nm or more and 25 nm or less from the viewpoint of thermal conductivity, more preferably 5 nm or more and 20 nm or less, further preferably 5 nm or more and 18 nm or less, and 7 nm or more and 14 nm or less. And particularly preferred.
It is simple and preferable to use small particles and large particles having a known average particle diameter as a raw material for the heat insulating material. When the average particle size is specified for commercially available small particles and large particles, the value can be regarded as the average particle size of each particle. There are various methods for measuring the particle diameter in commercial products, and there may be some variation in the diameter required depending on the measurement method, but the average particle diameter is 5 nm to 30 nm in the usual measurement method. If there is, it is certain that a plurality of small particles having a particle size of 5 nm or more and 30 nm or less are contained, and the average particle size of the large particles is not a difference because it does not affect the properties of the heat insulating material.
When the average particle diameter of the raw material is unknown, the average particle diameter of the small particles is assumed to be spherical, the specific surface area of the small particles is measured, and the following formula d = 6 / ρs
(Where d is the particle diameter [m], s is the specific surface area [m ² / g], and ρ is the density [g / cm ³ ])
Can be obtained. If the particles are not spherical, the average particle size determined from this formula may dissociate from the true value, but even in this case, if the average particle size is 5 nm or more and 30 nm or less, the particle size Since it is certain to contain a plurality of small particles of 5 nm or more and 30 nm or less, there is no problem. The specific surface area s [m ² / g] can be measured using nitrogen as an adsorption gas (nitrogen adsorption method). The BET method is adopted for the specific surface area. As a measuring apparatus, for example, a gas adsorption measuring apparatus (Autosorb 3MP, can be used Yuasa Ionics Corporation. Density ρ [g / cm ^3] refers to the true specific gravity obtained by pycnometer method. Measurements As an apparatus, for example, an automatic wet true density measuring device (Auto True Densor MAT-7000, manufactured by Seishin Enterprise Co., Ltd.) can be used, and the average particle size of large particles can be determined in the same manner as small particles.
When preparing a powder by mixing small particles and large particles, it is preferable to mix a set of small particles and a set of large particles, and each set has an average particle diameter. On the other hand, in the state of a powder containing small particles and large particles, there is no problem in terms of heat conduction, whether it is a continuous particle size distribution or a particle size distribution having a plurality of maximum values. It is sufficient to satisfy “including a plurality of small particles”. In addition, although the particle size distribution affects the maximum load, it is not a direct requirement that there are a plurality of maximum values. Therefore, it is necessary to satisfy “including a plurality of small particles” from the viewpoint of performance as a heat insulating material, and “average value of particle diameter” is specified as a characteristic of small particles and / or large particles contained in the powder. On the other hand, as a requirement on the manufacturing method, the inventors recognize that it is easy to obtain a heat insulating material having a desired thermal conductivity and maximum load by setting the average particle diameter of the raw material within a preferable range. It is.

Hereinafter, the raw material used for the manufacturing method of a heat insulating material and each process are demonstrated.
[2-1] Silica particles, alumina particles Silica particles and alumina particles are particles having a silica component and an alumina component, respectively, and the mixing ratio of small particles and large particles and the thermal conductivity may be adjusted. it can. For example, the silica particles may be particles produced by condensing silicate ions by a wet method under acidic or alkaline conditions. Silica particles may be obtained by hydrolyzing and condensing alkoxysilane by a wet method, or by baking a silica component produced by a wet method, or by producing a silicon compound such as chloride in the gas phase. You may have done. The silica particles may be produced by oxidizing and burning silicon gas obtained by heating a raw material containing silicon metal or silicon. The silica particles may be produced by melting silica or the like. For example, the alumina particles may be obtained by precipitating and filtering aluminum hydroxide from an aqueous solution of a soluble aluminum salt and igniting it. It may be obtained by the Bayer method based on the principle of manufacturing sodium aluminate by treating with gibbsite or boehmite with sodium hydroxide, or by giving gibbsite, boehmite, diaspore, clay, alumite, sulfuric acid, nitric acid, etc. It may be obtained by purifying the aluminum salt by treating with, separating the acid groups by precipitation with ammonia or pyrolysis, and baking.

Silica particles and alumina particles may contain components other than silica and components other than alumina, and examples thereof include those present as impurities in the raw material in the above production method. Components other than silica and alumina may be added during the production process of silica and alumina.

Known methods for producing silica include the following.
<Silica synthesized by wet method>
Gel silica made from sodium silicate and made acidic.
Precipitated silica made from sodium silicate and made alkaline.
Silica synthesized by hydrolysis and condensation of alkoxysilanes.

<Silica synthesized by dry method>
Fumed silica made by burning silicon chloride.
Silica obtained by vaporizing and oxidizing metals at high temperatures.
Silica fume by-produced during ferrosilicon production.
Silica produced by the arc method or plasma method.
Fused silica that melts and spheroidizes pulverized silica powder in a flame.

Known methods for producing alumina include the following.
Alumina obtained by acid method.
Alumina obtained by the buyer method (alkali method).
Sintered alumina obtained by granulating, drying and firing calcined alumina made by the Bayer method.
Fused alumina obtained by melting the raw material in an electric furnace and crystallizing it.
White fused alumina made from calcined alumina made by the buyer method.
Brown electrofused alumina mainly made of bauxite.
Fumed alumina.
Alumina obtained by vaporizing and oxidizing metal at high temperatures.

Of the silica obtained by each manufacturing method, gel method silica made acidic using sodium silicate as a raw material, precipitation method silica made alkaline using sodium silicate as a raw material, silica synthesized by hydrolysis and condensation of alkoxysilane Fumed silica made by burning silicon chloride, silica made by burning silicon metal gas, silica produced by arc method or plasma method, fumed alumina causes molding defects during pressure molding It's easy to do. Furthermore, they tend to scatter and tend to aggregate. By mixing silicas having different average particle diameters by the above-described method, it is possible to suppress molding defects, scattering, and aggregation, and therefore, including silica particles and alumina particles obtained by other production methods, a plurality of It is preferable to mix silica particles or alumina particles.

Silica fume by-produced during ferrosilicon production, fused silica that melts and spheroidizes crushed silica powder in a flame, alumina obtained by the Bayer method, sintered alumina, fused alumina (white fused alumina, brown Fused alumina) has a thermal conductivity of more than 0.05 W / m · K. Therefore, using only silica and alumina obtained by this production method as a raw material for silica particles and alumina particles is not a preferable aspect in terms of thermal conductivity, but is less scattered and excellent in handling. It may be useful in terms of cost. It is possible to adjust the thermal conductivity to 0.05 W / m · K or less by mixing silica obtained by other manufacturing methods, so when using silica fume, sintered alumina, etc. as a raw material It is preferable to mix silica particles and alumina particles obtained by other production methods. For example, fumed silica made by burning silicon chloride, silica made by burning silicon metal gas, silica particles containing silica fume, sintered alumina, and / or alumina by mixing fumed alumina. The thermal conductivity of the particles can be reduced.

Among the above silica and alumina, fumed silica, silica produced by burning silicon metal gas, silica fume, fused silica, fumed alumina, alumina obtained by the Bayer method, sintered alumina from the viewpoint of productivity and cost It is more preferable to use

It is possible to use natural silicate minerals as silica particles. Examples of natural minerals include olivine, chlorite, quartz, feldspar, zeolite and the like. Natural minerals can be used as an example of alumina particles. Examples of alumina natural minerals include bauxite, porphyry shale, mullite, sillimanite, kyanite, andalusite, and chamotte. The mullite may be synthetic mullite, sintered mullite, or electrofused mullite. A natural mineral is subjected to a treatment such as pulverization to adjust the particle diameter, and can be used as silica particles and / or alumina particles constituting the powder.

[2-2] Alkali metal element, alkaline earth metal element, Ge, P, Fe
During the manufacturing process of silica and alumina and the manufacturing process of the heat insulating material, they may be added as compounds containing basic elements, Ge, P and Fe, respectively, but a sufficient amount of basic elements, Ge, P and Fe are added. It is good also considering the silica particle and / or alumina particle which are contained beforehand as a raw material of a heat insulating material. The compound containing a basic element, Ge, P, Fe is not particularly limited. For example, basic elements, oxides of Ge, P, Fe, composite oxides, hydroxides, nitrides, carbides, carbonates, Examples include acetates, nitrates, ammonium salts, sparingly soluble salts, and alkoxides. These may be added alone or a mixture thereof may be added. Using inorganic compound particles containing silica containing basic elements, Ge, P, and Fe as impurities, as a raw material of the powder is a preferable embodiment from the viewpoint of productivity, cost, and workability. Such inorganic compound particles containing silica can be obtained, for example, as silica fume that replicates during the production of silica gel-derived particles or ferrosilicon produced by a precipitation method.

The method of adding a compound containing each of basic elements, Ge, P, and Fe is not particularly limited. For example, it may be added to silica obtained by the above wet method or dry method, alumina obtained by the acid method or alkali method, sintered alumina, electrofused alumina, or added in each of the above production steps of silica or alumina. May be. The compound containing each basic element, Ge, P, and Fe may be water-soluble or insoluble in water. It may be added as an aqueous solution of a compound containing basic elements, Ge, P, and Fe, and may be dried as necessary, or a compound containing basic elements, Ge, P, and Fe may be solid or liquid. You may add in a state. The compound containing each of the basic elements, Ge, P, and Fe may be previously pulverized to a predetermined particle diameter, or may be preliminarily coarsely pulverized.

When silica particles or alumina particles contain an excessive amount of basic elements, Ge, P, Fe, some processing is performed during the silica or alumina manufacturing process or the heat insulating material manufacturing process to contain the elements. The amount may be adjusted to a predetermined range. The method for adjusting an excessive amount of basic elements, Ge, P, and Fe to a predetermined range is not particularly limited. For example, as a method for adjusting the content of the basic element, there may be mentioned a substitution method, extraction method, removal method, etc. with an acidic substance or other elements. After treating inorganic compound particles containing silica with nitric acid or aqua regia, It can be dried and used as a raw material for powder. Adjustment of an excessive amount of basic elements, Ge, P, and Fe may be performed after previously pulverizing inorganic compound particles containing silica and / or alumina to a desired particle diameter, or basic elements, Ge, P, and the like. The silica particles and alumina particles may be pulverized after adjusting Fe to a predetermined range.

[2-3] Mixing method Silica particles and / or alumina particles, infrared opacifying particles and inorganic fibers used are known powder mixers, for example, those listed in the Revised Sixth Edition Chemical Engineering Handbook (Maruzen) And can be mixed. At this time, it is possible to mix two or more kinds of inorganic compound particles containing silica, or a compound containing each of basic elements, Ge, P, and Fe, or an aqueous solution thereof. Known powder mixers include a horizontal cylindrical type, a V type (which may be equipped with a stirring blade), a double cone type, a cubic type, and a shaking type as a container rotating type (the container itself rotates, vibrates and swings). Dynamic rotation type, mechanical agitation type (container is fixed and agitated with blades, etc.), single axis ribbon type, double axis paddle type, rotary saddle type, biaxial planetary agitation type, conical screw type, high speed agitation type, rotation Examples of the disk type, the rotating container type with roller, the rotating container type with stirring, the high-speed elliptical rotor type, and the fluid stirring type (stirring by air and gas) include an airflow stirring type and a non-stirring type by gravity. You may use combining these mixers.

Mixing silica particles and / or alumina particles, infrared opacifying particles and inorganic fibers can be performed by using a material known as a pulverizer, for example, those listed in the Revised Sixth Edition, Chemical Engineering Handbook (Maruzen). You may carry out, grind | pulverizing, cutting an inorganic fiber, or improving the dispersibility of particle | grains and an inorganic fiber. At this time, it is possible to pulverize and disperse two or more kinds of silica particles and / or alumina particles, or to pulverize and disperse a compound containing each of basic elements, Ge, P, and Fe and an aqueous solution thereof. Known pulverizers include roll mills (high pressure compression roll mills, roll rotating mills), stamp mills, edge runners (fret mills, Chillian mills), cutting / shearing mills (cutter mills, etc.), rod mills, self-pulverizing mills (erofall mills, Cascade mills, vertical roller mills (ring roller mills, rollerless mills, ball race mills), high-speed rotary mills (hammer mills, cage mills, disintegrators, screen mills, disc pin mills), high-speed rotary mills with built-in classifiers (fixed) Impact plate mill, turbo mill, centrifugal classification mill, annular mill, container drive medium mill (rolling ball mill (pot mill, tube mill, conical mill)), vibration ball mill (circular vibration mill, rotational vibration mill, centrifugal mill) ), Planetary mill, centrifugal fluidization mill), medium Stirring mill (tower crusher, stirring tank mill, horizontal flow tank mill, vertical flow tank mill, annular mill), airflow grinder (airflow suction type, nozzle passage type, collision type, fluidized bed) Jet blow type), compaction shear mill (high-speed centrifugal roller mill, inner piece type), mortar, stone mill and the like. You may use combining these grinders.

Among these mixers and pulverizers, powder mixers with stirring blades, high-speed rotary mills, high-speed rotary mills with built-in classifiers, container drive medium mills, and compaction shear mills improve the dispersibility of particles and inorganic fibers. Therefore, it is preferable. In order to improve the dispersibility of the particles and inorganic fibers, it is preferable to set the peripheral speed of the tip of the stirring blade, rotating plate, hammer plate, blade, pin, etc. to 100 km / h or more, more preferably 200 km / h or more, More preferably, it is 300 km / h or more.

When mixing a plurality of types of silica particles and / or alumina particles, it is preferable to introduce the silica particles and / or alumina particles into a stirrer or pulverizer in the order of increasing bulk specific gravity. When inorganic fibers and infrared opaque particles are included, it is preferable to add and mix infrared opaque particles after mixing silica particles and / or alumina particles, and then add and mix inorganic fibers.

In addition to or instead of inorganic fibers and infrared opaque particles, a metal oxide sol may be added to silica particles or alumina particles. The metal oxide sol becomes an inorganic binder, and a molded article having high compressive strength can be easily obtained. When mixing a plurality of types of silica particles, from the viewpoint of highly dispersing the metal oxide sol throughout the molded body, for example, after mixing small particles and large particles in advance by the above-described method, the metal oxide sol is added. It is preferable to mix. When mixing the metal oxide sol, as in the case of mixing small particles and large particles, using a pulverizer equipped with a known stirring blade, pulverize the particles, cut the inorganic fiber, While improving the dispersibility of the particles and inorganic fibers, it is preferable to mix with the peripheral speed at the tip of the stirring blade being 100 km / h. In order to improve the dispersibility of the metal oxide sol, it is preferable to use a powder mixer having a stirring blade, and the peripheral speed at the tip of the stirring blade is preferably 100 km / h or more, and there is less contact between large particles. In view of the above, 200 km / h or more is more preferable, and 300 km / h or more is more preferable.

Examples of the metal oxide sol include silica sol, alumina sol, zirconia sol, ceria sol, and titania sol. Silica sol and alumina sol are preferable from the viewpoint of reducing thermal conductivity and heat resistance. The particle size of the metal oxide sol is preferably 2 nm or more and 450 nm or less, more preferably 4 nm or more and 300 nm or less, and further preferably 4 nm or more and 200 nm or less from the viewpoint of reducing the thermal conductivity.

From the viewpoint of preventing the mixture from adhering to the inner wall of the stirring tank and mixing from becoming uneven when mixing with silica, alumina, inorganic fibers, and infrared opaque particles, the amount of the metal oxide sol added is The content of the solid content of the metal oxide sol with respect to the total mass of is preferably 0.5% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 25% by mass or less, and further preferably 2% by mass or more and 25% by mass or less. preferable.

[2-4] Molding method The heat insulating material of the present embodiment can be obtained by pressure-molding an inorganic mixture as a raw material. In the molding step, the pressure treatment and the heat treatment are simultaneously performed (a). Alternatively, (b) heat treatment may be performed after the pressure treatment. That is, (a) a method of pressurizing a mold (molding die) filled (contained) with an inorganic mixture while heating may be used, or (b) an inorganic mixture is pressurized by pressurizing the mold with the inorganic mixture filled. After the molding, the obtained heat insulating material may be taken out from the mold or heated in a state of being put in the mold. In both embodiments, the preferred pressure and heating temperature are approximately the same.

As the pressure molding method, molding may be performed by a conventionally known ceramic pressure molding method such as a die press molding method (ram type pressure molding method), a rubber press method (hydrostatic pressure molding method), or an extrusion molding method. it can. From the viewpoint of productivity, a die press molding method is preferable.

When filling a mold with a powdery heat insulating material by a die press molding method or a rubber press method, the powdered heat insulating material is vibrated, etc., so that the thickness of the molded body is uniform. Therefore, it is preferable. Filling the mold with a powdery heat insulating material while reducing the pressure and degassing the mold is preferable from the viewpoint of productivity because the mold can be filled in a short time.

The bulk density of the resulting molded body is set under conditions for pressure molding from the viewpoint of making the maximum load and / or thermal conductivity at a compression rate of 0 to 5% as desired and reducing the burden during transportation. If preferably set to be less than 0.2 g / cm ³ or more 1.5 g / cm ^3. If the molding conditions are controlled by the pressurized pressure, the pressure is maintained depending on the slipperiness of the powder used as the raw material for the heat insulating material, the amount of air taken in between the particles of the powder and the pores, etc. Since the pressure value changes with time, production management tends to be difficult. On the other hand, the method of controlling the bulk density is preferable in that the load of the heat insulating material obtained without requiring time control can be easily set to the target value. The bulk density of the heat insulating material is more preferably 0.25 g / cm ³ or more and 1.2 g / cm ³ or less, and further preferably 0.30 g / cm ³ or more and 1.0 g / cm ³ or less. The molding pressure at which the bulk density of the molded body is 0.2 g / cm ³ or more and 1.5 g / cm ³ or less is, for example, a pressure of 0.01 MPa or more and 50 MPa or less, and 0.25 g / cm ³ or more and 1.2 g. / cm ³ as a molding pressure equal to or less than is the pressure below 40MPa example 0.01MPa or more, as the molding pressure equal to or less than 0.30 g / cm ³ or more 1.0 g / cm ³ 30 MPa or less, for example 0.01MPa or more Pressure.

An example of a method for producing a heat insulating material will be described so that the bulk density of the obtained heat insulating material becomes a predetermined size. First, the weight of the necessary inorganic mixture is obtained from the volume of the heat insulating material and the bulk density. Next, the weighed inorganic mixture is filled in a mold and pressed to a predetermined thickness and molded. Specifically, in the case of producing a molded body having a length of 30 cm, a width of 30 cm, a thickness of 20 mm and a bulk density of 0.5 g / cm ³ , the heat insulating material is obtained by multiplying the volume of the molded body to be manufactured to the target bulk density. It is possible to determine the weight of the powder necessary for the production. That is, in the example of the heat insulating material described above, 0.5 [g / cm ³ ] × 30 [cm] × 30 [cm] × 2 [cm] = 900 [g], and necessary powder is 900 g.

Generally speaking, when producing a molded body having a volume αcm ³ and a bulk density of βg / cm ³ (where β is larger than the loosely packed bulk density of the powder), the powder is weighed by αβg, and the powder Is compressed so as to have a volume α.

[2-5] Heat treatment method The heat insulating material during or after pressure molding is heat-dried within the range of temperature and time sufficient for the heat resistance of the heat insulating material, and the adsorbed water of the heat insulating material. It is preferable to put it to practical use after removing it because the thermal conductivity is lowered. Furthermore, you may heat-process.

Molding may be only pressure molding, but it is preferable to heat-treat the pressure-molded one. The heat treatment may be performed during pressure molding. When heat treatment is performed on a powder that is a raw material of a heat insulating material, the compression strength is improved and the powder can be used particularly suitably in applications where the load is large. From the viewpoint of improving the productivity of the heat treatment, the heat insulating material preferably contains an alkali metal element, an alkaline earth metal element, Ge, P, or Fe, and particularly preferably contained in a large particle.

From the viewpoint of dimensional stability, the heat treatment temperature is preferably higher than the maximum use temperature of the heat insulating material. Although it changes with uses of a heat insulating material, 400 to 1400 degreeC is preferable specifically, More preferably, it is 500 to 1300 degreeC, More preferably, it is 600 to 1200 degreeC.

In order to set the maximum load at a compression rate of 0 to 5% to 0.7 MPa or more, the heat insulating material can contain the metal oxide sol as described above. When the heat insulating material contains a metal oxide sol, the heat insulating material tends to be hardened at a lower heat treatment temperature. Specifically, the heat insulating material is preferably 200 ° C. or higher and 1400 ° C. or lower, more preferably 300 ° C. or higher and 1300 ° C. It is 400 degreeC or more, More preferably, it is 1200 degreeC or less.

The heat treatment atmosphere of the heat insulating material is in the air (or in the air), in an oxidizing atmosphere (oxygen, ozone, nitrogen oxide, carbon dioxide, hydrogen peroxide, hypochlorous acid, inorganic / organic peroxide, etc.) And in an inert gas atmosphere (helium, argon, nitrogen, etc.). Water vapor may be added to the atmosphere. The heat treatment time may be appropriately selected according to the heat treatment temperature and the amount of the heat insulating material. The heat treatment may be performed after the heat insulating material is installed at a place where the heat insulating material is used, or may be applied in advance to the heat insulating material before installation or construction.

[2-6] Method for Producing Cut Heat Insulating Material The heat insulating material of the present embodiment can be cut to obtain a cut heat insulating material. As a method for producing cutting the insulation, molding comprises silica and / or alumina, a housing step of the inorganic mixture having a particle diameter D _S contains small particles is 5nm or 30nm or less, to accommodate the mold, the inorganic mixture A forming step, that is, a step of heating to 400 ° C. or higher while pressing the inorganic mixture with a mold, or a step of forming a heat treatment at a temperature of 400 ° C. or higher after forming the inorganic mixture by pressing, and a molding step A cutting step of cutting a part of the obtained heat insulating material. The cutting means for the heat insulating material is not particularly limited. A vertical machining center, a horizontal machining center, a milling machine such as a 5-axis machine can be used, and a hand saw, a lathe, and a milling machine are particularly preferable.

Here, in the manufacturing method of the cut heat insulating material, from the viewpoint of making it difficult to disintegrate at the time of cutting and processing, large particles having an inorganic compound containing silica and / or alumina and having a particle diameter _DL of 50 nm or more and 100 μm or less are used. It is preferable to include the step of mixing the large particles with a ratio _RL of the mass of the large particles to the total mass of the small particles and the large particles being 60% by mass to 90% by mass to obtain an inorganic mixture. Preferably, the large particles preferably contain at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and germanium. In the molding step, the bulk density of the heat insulating material is 0.2 g / cm. ³ to 1.5 g / cm ³ by setting the molding pressure to be less than is preferred.

[3] Heat insulation enveloping body provided with outer covering material It is preferable that the heat insulating material is an insulating material enveloping body provided with the heat insulating material and the outer covering material that accommodates the heat insulating material. A heat insulating material enveloping body provided with a covering material has an advantage that it is easy to handle and easy to construct as compared with a heat insulating material not including a covering material. In addition, the heat insulating material accommodated in the jacket material may be referred to as a core material.

FIG. 3 is an example of a schematic cross-sectional view of a heat insulating material enveloping body according to the present embodiment. FIG. 4 is an example of a schematic cross-sectional view of small particles and large particles according to the present embodiment. As shown in FIGS. 3 and 4, the heat insulating material encapsulating body 1 according to the present embodiment includes a plurality of small particles S and a plurality of large particles L having a particle diameter larger than that of the small particles S. 2 and a jacket material 3 for housing the heat insulating material 2. In the heat insulating material 2, the small particles S and the large particles L are mixed, and the small particles S exist around the large particles L.

[3-1] Cover Material The cover material is not particularly limited as long as it can accommodate a heat insulating material as a core material. Examples thereof include inorganic fiber fabrics such as glass cloth, alumina fiber cloth, silica cloth, and inorganic fibers. Knitted fabric, polyester film, polyethylene film, polypropylene film, nylon film, polyethylene terephthalate film, resin film such as fluororesin film, plastic-metal film, metal foil such as aluminum foil, stainless steel foil, copper foil, ceramic paper, inorganic fiber Nonwoven fabric, organic fiber nonwoven fabric, glass fiber paper, carbon fiber paper, rock wool paper, inorganic filler paper, organic fiber paper, ceramic coating, fluororesin coating, siloxane resin coating, and other resin coatings can be exemplified. From the viewpoint of reducing the heat capacity of the jacket material, it is preferable that the thickness of the jacket material is thin. When the jacket material is made of a material that is stable at the temperature at which the core material is used, the jacket material is in a state of accommodating a heat insulating material that is the core material even during use. In the case of a heat insulating material provided with a jacket material used at a high temperature, a jacket material having high heat resistance is preferable from the viewpoint of easy handling of the core material after use. "" Includes the core material accommodated in the process of transporting and constructing the core material in addition to the core material accommodated when the core material is used. In other words, the jacket material protects the core material only during transportation and construction, and includes those that melt and / or volatilize during use. Therefore, the organic material contained in the jacket material itself or the jacket material is the core. It may melt or disappear at the use temperature of the material.

From the viewpoint that the coating process is easy, inorganic fiber fabrics such as glass cloth, alumina fiber cloth, silica cloth, inorganic fiber knitted fabric, polyester film, polyethylene film, polypropylene film, nylon film, polyethylene terephthalate film, fluorine Resin film such as plastic resin film, plastic-metal film, metal foil such as aluminum foil, stainless steel foil, copper foil, ceramic paper, inorganic fiber nonwoven fabric, organic fiber nonwoven fabric, glass fiber paper, carbon fiber paper, rock wool paper, inorganic Sheet shapes such as filled paper and organic fiber paper are preferred.

In the case where a heat insulating material enveloping body provided with a covering material is used at a high temperature, the covering material is made of an inorganic fiber woven fabric such as glass cloth, alumina fiber cloth, silica cloth, or inorganic fiber knitted fabric from the viewpoint of thermal stability. Ceramic paper and inorganic fiber nonwoven fabric are more preferable. The jacket material is more preferably an inorganic fiber fabric from the viewpoint of strength.

[3-2] Method of coating with outer jacket material Insulation containing silica particles and / or alumina particles, adding large particles, infrared opacifying particles and inorganic fibers depending on the usage, and optionally heat treatment The material may be a core material and may be covered with a jacket material. As will be described later, both the powder, which is a raw material of the heat insulating material, and the jacket material may be pressure-molded together, or the powder, which is the raw material of the heat insulating material, is subjected to pressure molding and heat treatment to obtain a heat insulating material. It is also possible to coat with a jacket material after a while.

The method of coating the core material with the jacket material is not particularly limited, and the core material may be prepared or molded and coated with the jacket material at the same time, or the core material may be coated with the jacket material after preparation or molding. May be.

Cover material is inorganic fiber fabric, resin film, plastic-metal film, metal foil, ceramic paper, inorganic fiber nonwoven fabric, organic fiber nonwoven fabric, glass fiber paper, carbon fiber paper, rock wool paper, inorganic filler paper, organic fiber paper, etc. In the case of the sheet-like form, for example, it is possible to cover with stitching with inorganic fiber yarn or resin fiber yarn, adhesion fixing of the jacket material, and both stitching and adhesion.

When the jacket material is a resin film, a plastic-metal film, a metal foil or the like, a vacuum pack or a shrink pack is preferable from the viewpoint of easy coating process.

When the jacket material is ceramic coating, resin coating, or the like, the core material can be covered with the jacket material by applying to the core material with a brush or spray.

It is also possible to provide a linear depression in a heat insulating material composed of a pressure-molded core material and a jacket material to give flexibility to the heat insulating material. As the form of the line, a linear shape, a curved shape, a broken line shape, or the like can be selected according to the use state of the heat insulating material, and two or more of these may be combined. The thickness of the line and the depth of the depression are determined according to the thickness, strength, and usage of the heat insulating material.

The outer jacket material may cover the entire surface of the core material, or may partially cover the core material.

[4] Application The heat insulating material of the present embodiment is a heat absorbing material, a sound absorbing material, a sound insulating material, a sound insulating material, an anti-reflection material, a sound deadening material, an abrasive, a catalyst carrier, an adsorbent, a fragrance, a bactericide, and the like. It can also be suitably used for a carrier that adsorbs water, a deodorant, a deodorant, a humidity control material, a filler, a pigment, and the like.

[4-1] Heat insulation method The heat insulating material of the present embodiment is adhered to a heat resistant container to maintain the temperature in the container or prevent the heat in the container from diffusing. It is possible to use suitably for the heat insulation method. In the heat source and the container that accommodates the heat source, if a heat insulating material is provided so as to be interposed between the heat source and the container, heat transfer from the heat source to the container can be suppressed. In this case, if the heat insulating material is shaped to fit into the container (for example, when the container is cylindrical, the heat insulating material is formed into a cylindrical shape having the same outer diameter as the inner diameter of the container), etc. Although it is not necessary to stick a heat insulating material to a container, a sticking is a preferable aspect from a viewpoint of stability of a heat insulating material.

The heat-resistant container is not particularly limited, and examples thereof include a molten iron container, a ladle, a tundish, a topped car, a glass manufacturing container, a melting furnace, a boiler, a steel plate duct, a steam tank, and an engine. In the present specification, the “heat-resistant container” may have any shape that can be accommodated therein, and is not limited in size and mobility, and is a concept that includes what is generally called “furnace”. Therefore, steel heating furnaces used in steel plants, metal heat treatment furnaces used in non-ferrous metal production, aluminum melting furnaces, aluminum holding furnace lids, various industrial furnaces such as glass production, carbon firing furnaces, naphtha cracking furnaces, In addition to various furnaces such as ceramic firing furnaces, semiconductor heat treatment furnaces, refuse incinerators, reforming furnaces, kiln furnaces, firing furnaces, heating furnaces, kilns, various towers or tanks, and containers constituting heat exchangers and turbines The shape is also included in the heat resistant container. Since the heat insulating material of this embodiment is excellent in pressure resistance, it can be suitably used particularly in a place where pressure is applied.

Although the sticking method is not particularly limited, a method of sticking through a binder and / or a refractory is preferable from the viewpoint of ease of construction. The binder has the function of fixing the heat insulating material to the heat resistant container, the function of absorbing the vibration of the heat resistant container and / or the heat insulating material, the heat from the joint filled with the heat insulating material, and the contents of the heat resistant container ( Those having a function of suppressing the outflow of gas (including gas) are also included.

Examples of the binder include mortar, adhesive, fixing agent, and bonding agent, and various tapes such as a tape, a double-sided tape, and an acrylic resin-based adhesive tape can be used as the binder. Examples of the adhesive include silica-based adhesive, ceramic, cement, solder, inorganic adhesive such as water glass (sodium silicate, sodium silicate), organic adhesive, asphalt, gum arabic, albumin, lacquer, glue, pine Natural adhesives such as, acrylic resin adhesive, acrylic resin anaerobic adhesive, α-olefin adhesive, urethane resin adhesive, ethylene-vinyl acetate resin emulsion adhesive, epoxy resin adhesive, epoxy resin Emulsion adhesive, vinyl acetate resin emulsion adhesive, cyanoacrylate adhesive, silicone adhesive, aqueous polymer-isocyanate adhesive, phenol resin adhesive, modified silicone adhesive, polyimide adhesive, polyacetic acid Synthetic adhesives such as vinyl resin solution adhesives, polybenzimidazole adhesives, etc. And the like.

Refractories include heat-resistant bricks, refractory bricks, irregular refractories, refractory mortars, refractory stamp materials, and refractory insulation bricks. Moreover, even if it is generally classified as a heat insulating brick, it is contained in a refractory material as long as it has fire resistance. Refractories can be classified into acidic refractories, neutral refractories, basic refractories, non-oxide refractories, and composite refractories. Examples of acidic refractories include feldspar, fused quartz, waxy, clay, high alumina, zircon, AZS, and zirconia refractories. Examples of neutral refractories include alumina and chromia refractories. Examples of basic refractories include calcareous, dolomite, magnesia, chromium magnesia, and spinel refractories. Examples of the non-oxide refractories include carbonaceous, silicon carbide, silicon carbide-graphite, and silicon nitride refractories. Examples of the composite refractories include alumina / carbonaceous, magnesia / carbonaceous, and silicon carbide-containing refractories.

The heat insulating material of the present embodiment may be attached to a heat-resistant container through a binder, may be attached to a heat-resistant container through a refractory, or a heat-resistant container through both a binder and a refractory. You may stick to. A mode in which the molded body and / or the encapsulated body is attached to a heat-resistant container via a refractory is suitable for applications that require heat resistance in addition to heat insulation. For example, when a container to be insulated contains a heat source and a heat insulating material is provided outside the container for heat insulation, the heat insulating material is thermally deteriorated due to the presence of a refractory between the heat insulating material and the container. It is possible to prevent this, and to maintain the heat insulation performance for a long time. Or the form which provided the refractory inside the container and provided the heat insulating material outside the container may be sufficient. Therefore, since the frequency | count of replacement | exchange of a heat insulating material can be reduced and the frequency which stops the apparatus containing the said heat-resistant container for replacement | exchange work can be reduced, the improvement of productivity is anticipated. On the other hand, when the heat from the heat source contained in the container is insulated, if a heat insulating material is provided inside the container and a refractory is further provided inside the container, the refractory is interposed between the heat source and the heat insulating material. Therefore, heat conduction to the heat-resistant container can be suppressed while preventing deterioration of the heat insulating material. The heat insulating material and / or the refractory does not need to cover the entire surface of the container, and even if it is partially, there is an effect of heat insulation and / or prevention of deterioration accordingly. However, in that case, since the effect of heat insulation or the like is reduced by heat transfer from the uncoated portion, it is preferable that each cover the entire inner surface. In order to cover the entire surface of the container, the heat insulating material and the refractory material may have substantially the same shape as the container, but the thickness of each may be appropriately set according to the required heat insulation and / or fire resistance performance.

In addition, the heat insulating material different from the present embodiment may be sandwiched between the heat insulating material of the present embodiment and / or the heat insulating material.

The heat insulating material of this embodiment can be attached to a heat-resistant container using screws. Here, the screw includes a bolt, a nut, and a screw. The heat insulating material of this embodiment can be drilled with a hand drill or the like and screwed. When attaching via a binder or a refractory, a screw may be used. For example, when the area and / or weight of the heat insulating material to be used is large, the heat resistance performance of the adhesive is insufficient, and when screws are used for construction on the ceiling surface, there is a tendency that adhesion is easy. Moreover, also when a sticking location vibrates, there exists a tendency for fixation by screwing to be effective. On the other hand, when the heat insulating material has a jacket material or when the location where the heat insulating material is pasted is a curved surface, the use of a binder tends to be suitable, but the type of heat insulating material, the situation of the location where it is to be pasted The binder, the refractory, and the screw may be appropriately selected according to the contents of the sticking process.

The heat insulating material according to the present embodiment is housed in a housing to maintain the temperature in the housing, to diffuse the heat in the housing, and to prevent the housing from taking in external heat. It is also possible to use it suitably. The housing is not particularly limited, and examples include a fuel cell unit, a fuel cell module housing, a fuel cell power generation unit, a stove, and a water heater. The method of housing in the housing is not particularly limited, and it may be simply filled and arranged in the housing, or may be attached to the inner wall of the housing, for example, via the binder and / or refractory as described above, or screwed. It can be housed in a case by sticking and fixing using a binder, or sticking using a binder, a refractory, and a screw.

The heat insulation method of covering the heat-resistant containers and pipes with the heat insulating material is effective for maintaining the internal temperature of the heat-resistant containers and pipes and conversely preventing heat from entering them. In order to cover the heat-resistant container and the pipe with the heat insulating material, a method of forming the heat insulating material in a shape slightly larger than the heat-resistant container and the pipe and fitting the heat-resistant container and the pipe therein can be adopted. For example, in order to cover a pipe, a semi-cylindrical shaped body having a slightly larger radius than the pipe may be produced and fitted so as to cover the pipe. Moreover, you may fix a heat insulating material around a heat-resistant container or piping with a wire etc. In order to insulate the pipe, a method of winding an elongated cylindrical enveloping body around the pipe is simple and effective.

[5] Measurement of parameters The compressive strength of the heat insulating material, the thermal conductivity, the particle diameter D _S of the small particles, the cumulative pore volume, the content of alkali metal elements, etc. are measured by the following method.

[Measurement of compressive strength]
The heat insulating material is processed to a length of 2 cm, a width of 2 cm, and a thickness of 2 cm, and the compressive strength is measured at an indentation speed of 0.5 mm / min using a precision universal testing machine Autograph AG-100KN (manufactured by Shimadzu Corporation).

[Measurement of thermal conductivity]
Using a heat insulating material having a shape of 30 cm in length, 30 cm in width and 20 mm in thickness as a measurement sample, the heat conductivity at 30 ° C. is measured using a heat flow meter HFM 436 Lambda (trade name, manufactured by NETZSCH). taking measurement. The calibration is performed according to JIS A1412-2 using a NIST SRM 1450c calibration standard plate having a density of 163.12 kg / m ³ and a thickness of 25.32 mm under the condition that the temperature difference between the high temperature side and the low temperature side is 20 ° C. 20, 24, 30, 40, 50, 60, and 65 ° C. in advance. The thermal conductivity at 800 ° C. is measured according to the method of JIS A 1421-1. Two heat insulating materials having a disk shape with a diameter of 30 cm and a thickness of 20 mm are used as measurement samples, and a protective hot plate method thermal conductivity measuring device (manufactured by Eiko Seiki Co., Ltd.) is used as a measuring device.

[Measurement of particle diameter _{D S} of the small particles]
Using a cross-section polisher (SM-09010, manufactured by JEOL Ltd.), subjecting the thermal insulation as a sample to BIB (broad ion beam) processing under the conditions of an acceleration voltage of 4.0 kV and a processing time of 9 hours, obtain. This sample is loaded on a sample stage, and Os coating of about 2 nm is performed using an osmium coater (HPC-1SW type, manufactured by Vacuum Device Co., Ltd.) to obtain a sample for speculum. As a speculum, a scanning electron microscope (S-4700, manufactured by Hitachi, Ltd.) is used, and one field of view is observed under the condition of an acceleration voltage of 1.0 kV. When two or more small particles are not observed in the visual field, 100 visual fields or more are observed to check whether 100 or more particles having an equivalent area equivalent circle diameter of 5 nm to 30 nm are present. The In calculating the particle diameter D _S of the small particles, equal area circle equivalent diameter by increasing the field number to be observed as needed to 30nm or smaller particles than 5nm were observed more than 100, the number average about 100 particles It shows the calculated values in the examples as the particle diameter D _S of the small particles.

[Measurement of integrated pore volume]
Measurement is performed by mercury porosimetry using a pore distribution measuring device Autopore 9520 (manufactured by Shimadzu Corporation). The formed heat insulating material is cut into a rectangular parallelepiped so as to enter the cell, one is taken into a low-sensitivity cell, and the pressure is measured under conditions of an initial pressure of about 7 kPa (about 1 psia, pore diameter of about 180 μm). The mercury parameters are set at the instrument default mercury contact angle of 130 degrees and the mercury surface tension of 485 dynes / cm.

[Measurement of content of alkali metal elements, etc.]
A powdered heat insulating material is pulverized in a menor mortar, filled into a 30 mmφ polyvinyl chloride ring, and pressure-molded with an XRF tablet molding machine to produce a tablet, which is used as a measurement sample. This is measured with a fluorescent X-ray analyzer RIX-3000 manufactured by Rigaku Corporation. Also in the case of the molded heat insulating material, the content of the alkali metal element or the like can be similarly measured by pulverizing with a menor mortar after making the size into a menor mortar.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Those skilled in the art can implement various modifications as well as the following embodiments, and such modifications are also included in the scope of the claims of the present invention. In addition, the measurement of the compressive strength, the measurement of thermal conductivity, the measurement of the integrated pore volume, and the measurement of the content of alkali metal elements and the like in the examples and comparative examples were as described above.

[Example 1]
A silica powder was obtained in which 25% by mass of silica powder (small particles) having an average particle size of 14 nm and 75% by mass of silica powder (large particles) having an average particle size of 150 nm were uniformly mixed by a hammer mill. In order to obtain a molded body with a length of 30 cm, a width of 30 cm, a thickness of 20 mm, and a bulk density of 0.50 g / cm ³ , 900 g of silica powder is filled in a mold having an inner dimension of 30 cm in length and 30 cm in width, and pressure molding is performed. As a result, a molded body having a bulk density of 0.50 g / cm ³ was obtained. This molded body was subjected to heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 1. Example 1 of the cross section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then such change the field of view as required to measure the particle diameter of the total of 100 small particles, the number average result, _{D S} is 16 nm, the thermal conductivity at 30 ℃ 0.0269W / m · The heat insulating material was cut in the vertical direction to produce 25 cut heat insulating materials having a length of 6 cm, a width of 6 cm, and a thickness of 20 mm. None of these cut heat insulating materials were chipped or damaged. Further, the heat insulating material cut by 6 cm in length, 6 cm in width, and 20 mm in thickness was cut and processed into 2 cm in length, 2 cm in width, and 2 cm in thickness, and the compressive strength was measured. The fracture point was indicated, and the load at this time was 3.57 MPa. The bulk density of the heat insulating material of Example 1 is 0.50 g / cm ³ , and the pore volume, that is, the cumulative pore volume V _0.003 of pores having a pore diameter of 0.003 μm to 150 μm is 0. The ratio of the cumulative pore volume V of pores having a pore diameter of 0.05 μm or more and 0.5 μm or less to R, ie, V _0.003 , was 97.8%.

[Example 2]
A silica powder in which 15% by mass of silica powder (small particles) having an average particle size of 12 nm and 85% by mass of silica powder (large particles) having an average particle size of 10 μm were uniformly mixed by a hammer mill was obtained. Using 1980 g of this silica powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 1000 ° C. for 10 hours to obtain a heat insulating material of Example 2. Example 2 of the cross section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then such change the field of view as required to measure the particle diameter of the total of 100 small particles, the number average result, _{D S} is 19 nm, the thermal conductivity at 30 ℃ 0.0479W / m · K, and 25 heat-insulating materials were cut and cut in the same manner as in Example 1, and none of these cut heat-insulating materials were chipped or damaged. Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 1.38 MPa. Moreover, the bulk density of the heat insulating material of Example 2 was 1.1 g / cm ³ , the pore volume was 1.258 mL / g, and R was 84.3%.

[Example 3]
A silica powder in which 90% by mass of silica powder (small particles) having an average particle diameter of 7.5 nm and 10% by mass of silica powder (large particles) having an average particle diameter of 60 μm were uniformly mixed by a hammer mill was obtained. . Using 396 g of this silica powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 3. Example 3 of the cross section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, D _S is 9 nm, the thermal conductivity at 30 ℃ 0.0331W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 3, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 1.14 MPa. Moreover, the bulk density of the heat insulating material of Example 3 was 0.22 g / cm ³ , the pore volume was 2.701 mL / g, and R was 48.7%.

[Example 4]
A silica powder in which 50% by mass of silica powder (small particles) having an average particle size of 14 nm and 50% by mass of silica powder (large particles) having an average particle size of 80 nm were uniformly mixed by a hammer mill was obtained. Using 558 g of this silica powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 1000 ° C. for 5 hours to obtain a heat insulating material of Example 4. Example 4 a cross-section of heat insulating material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 15 nm, the thermal conductivity at 30 ℃ 0.0213W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 4, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 0.98 MPa. Moreover, the bulk density of the heat insulating material of Example 4 was 0.32 g / cm ³ , the pore volume was 1.703 mL / g, and R was 67.4%.

[Example 5]
A silica powder in which 30% by mass of silica powder (small particles) having an average particle diameter of 7.5 nm and 70% by mass of silica powder (large particles) having an average particle diameter of 6 μm were uniformly mixed by a hammer mill was obtained. . Using 882 g of this silica powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 24 hours to obtain a heat insulating material of Example 5. Example 5 of the cross section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result for this, D _S is 9 nm, the thermal conductivity at 30 ℃ 0.0339W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 5, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 0.77 MPa. Moreover, the bulk density of the heat insulating material of Example 5 was 0.49 g / cm ³ , the pore volume was 1.048 mL / g, and R was 47.2%.

[Example 6]
A silica powder in which 80% by mass of silica powder (small particles) having an average particle diameter of 14 nm and 20% by mass of silica powder (large particles) having an average particle diameter of 150 nm was uniformly mixed by a hammer mill was obtained. Using 450 g of this silica powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 24 hours to obtain a heat insulating material of Example 6. Example 6 result the cross section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result for this, _{D S} is 16 nm, the thermal conductivity at 30 ℃ 0.0208W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 6, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 1.14 MPa. Moreover, the bulk density of the heat insulating material of Example 6 was 0.25 g / cm ³ , the pore volume was 2.426 mL / g, and R was 47.6%.

[Example 7]
A powder in which 20% by mass of silica powder (small particles) having an average particle size of 14 nm and 80% by mass of alumina powder (large particles) having an average particle size of 200 nm were uniformly mixed by a hammer mill was obtained. Using 1296 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, and then heat treatment was performed at 1100 ° C. for 5 hours to obtain a heat insulating material of Example 7. Example 7 result the cross section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result for this, _{D S} is 19 nm, the thermal conductivity at 30 ℃ 0.0283W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 as in Example 1, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point at a compression rate of 4.3%, and the load at this time was 1.12 MPa. Moreover, the bulk density of the heat insulating material of Example 7 was 0.73 g / cm ³ , the pore volume was 1.252 mL / g, and R was 87.6%.

[Example 8]
A silica powder was obtained in which 25% by mass of silica powder (small particles) having an average particle size of 22 nm and 75% by mass of silica powder (large particles) having an average particle size of 150 nm were uniformly mixed by a hammer mill. Using 936 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 8. Example 8 result the cross section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 23 nm, the thermal conductivity at 30 ℃ 0.0278W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 8, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 3.49 MPa. Moreover, the bulk density of the heat insulating material of Example 8 was 0.52 g / cm ³ , the pore volume was 1.518 mL / g, and R was 90.0%.

[Example 9]
A silica powder was obtained in which 25% by mass of silica powder (small particles) having an average particle size of 14 nm and 75% by mass of silica powder (large particles) having an average particle size of 80 nm were uniformly mixed by a hammer mill. 792 g of this powder was subjected to pressure molding in the same manner as in Example 1 to obtain a molded body, and then subjected to heat treatment at 1100 ° C. for 3 hours to obtain a heat insulating material of Example 9. Example 9 a cross-section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 18 nm, the thermal conductivity at 30 ℃ 0.0437W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 9, but there was no chipping or breakage in any of these cut heat insulating materials. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 2.59 MPa. Moreover, the bulk density of the heat insulating material of Example 9 was 0.47 g / cm ³ , the pore volume was 1.195 mL / g, and R was 90.6%.

[Example 10]
A silica powder was obtained by uniformly mixing 40% by mass of silica powder (small particles) with an average particle size of 7.5 nm and 60% by mass of silica powder (large particles) with an average particle size of 100 μm using a hammer mill. . Using 846 g of this powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 2 hours to obtain a heat insulating material of Example 10. Example 10 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, D _S is 9 nm, the thermal conductivity at 30 ℃ 0.0492W / M · K, 25 heat-insulating materials were cut and cut in the same manner as in Example 1 of the heat-insulating material of Example 10, but none of these cut-insulated materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point at a compression rate of 4.9%, and the load at this time was 6.29 MPa. Moreover, the bulk density of the heat insulating material of Example 10 was 0.60 g / cm ³ , the pore volume was 0.581 mL / g, and R was 32.87%.

[Example 11]
A powder in which 15% by mass of alumina powder (small particles) having an average particle size of 7 nm and 85% by mass of silica powder (large particles) having an average particle size of 80 nm were uniformly mixed by a hammer mill was obtained. Using 972 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, and then heat treatment was performed at 1100 ° C. for 5 hours to obtain a heat insulating material of Example 11. Example 11 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, D _S is 8 nm, the thermal conductivity at 30 ℃ 0.0279W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 11, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point when the compression rate was 4.6%, and the load at this time was 2.83 MPa. Moreover, the bulk density of the heat insulating material of Example 11 was 0.59 g / cm ³ , the pore volume was 0.965 mL / g, and R was 91.3%.

[Example 12]
A powder in which 15% by mass of silica powder (small particles) having an average particle size of 14 nm and 85% by mass of silica powder (large particles) having an average particle size of 320 nm was uniformly mixed by a hammer mill was obtained. Using 972 g of this powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 10 hours to obtain a heat insulating material of Example 12. Example 12 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 16 nm, the thermal conductivity at 30 ℃ 0.0327W / M · K, 25 heat insulating materials were cut and cut as in Example 1 in the same manner as in Example 1, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point at a compression rate of 4.7%, and the load at this time was 1.09 MPa. Moreover, the bulk density of the heat insulating material of Example 12 was 0.54 g / cm ³ , the pore volume was 1.027 mL / g, and R was 85.0%.

[Example 13]
A powder in which 20% by mass of silica powder (small particles) having an average particle size of 7.5 nm and 80% by mass of silica powder (large particles) having an average particle size of 10 μm were uniformly mixed by a hammer mill was obtained. Using 1260 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 1000 ° C. for 10 hours to obtain a heat insulating material of Example 13. Example 13 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 10 nm, the thermal conductivity at 30 ℃ 0.0439W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 13 of the heat insulating material of Example 13, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 0.97 MPa. Moreover, the bulk density of the heat insulating material of Example 13 was 0.72 g / cm ³ , the pore volume was 1.425 mL / g, and R was 79.8%.

[Example 14]
After uniformly mixing 21% by mass of silica powder (small particles) with an average particle size of 14 nm and 63% by mass of silica powder (large particles) with an average particle size of 150 nm using a hammer mill, the average particle size is 1 μm. Then, 16% by mass of zirconium silicate, which is an infrared opaque particle, was added and mixed uniformly to obtain a powder. Using 1044 g of this powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 14. Example 14 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 16 nm, the thermal conductivity at 30 ℃ 0.0413W / M · K, 25 heat insulation materials were cut and cut in the same manner as in Example 1 in Example 14, but none of these cut insulation materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point at a compression rate of 4.5%, and the load at this time was 3.58 MPa. Moreover, the bulk density of the heat insulating material of Example 14 was 0.58 g / cm ³ , the pore volume was 1.212 mL / g, and R was 89.3%. Moreover, after using this powder and performing pressure forming using a cylindrical mold having an inner diameter of 30 cm to obtain a molded body, it was subjected to a heat treatment at 900 ° C. for 5 hours to obtain a diameter of 30 cm and a thickness of Two disc-shaped heat insulating materials having a diameter of 20 mm and a bulk density of 0.58 g / cm ³ were obtained. Using these two heat insulating materials, the thermal conductivity at 800 ° C. was measured and found to be 0.0937 W / m · K.

[Example 15]
After 24% by mass of silica powder (small particles) having an average particle diameter of 14 nm and 71% by mass of silica powder (large particles) having an average particle diameter of 150 nm are uniformly mixed with a hammer mill, the average fiber diameter is 11 μm, 5 mass% of glass fibers having an average fiber length of 6.4 mm and a heat resistant temperature of 1050 ° C. were added and mixed with a high-speed shear mixer to obtain silica powder. Using 936 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 15. Example 15 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 16 nm, the thermal conductivity at 30 ℃ 0.0343W It was / m · K, and 25 sheets of the heat insulating material were cut and cut in the same manner as in Example 1 in Example 15, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point at a compression rate of 4.7%, and the load at this time was 3.84 MPa. Moreover, the bulk density of the heat insulating material of Example 14 was 0.52 g / cm ³ , the pore volume was 1.324 mL / g, and R was 83.5%.

[Example 16]
After uniformly mixing 21% by mass of silica powder (small particles) with an average particle size of 14 nm and 63% by mass of silica powder (large particles) with an average particle size of 80 nm using a hammer mill, the average particle size is 1 μm. Then, 15 mass% of zirconium silicate which is an infrared opaque particle is added and mixed uniformly. Further, 1 mass% of glass fiber having an average fiber diameter of 11 μm, an average fiber length of 6.4 mm, and a heat resistant temperature of 1050 ° C. The mixture was added and mixed with a high-speed shear mixer to obtain a powder. Using 864 g of this powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 1000 ° C. for 5 hours to obtain a heat insulating material of Example 16. Example 16 a cross-section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 18 nm, the thermal conductivity at 30 ℃ 0.0269W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 of Example 16, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 0.90 MPa. Moreover, the bulk density of the heat insulating material of Example 16 was 0.48 g / cm ³ , the pore volume was 1.613 mL / g, and R was 50.2%. Moreover, after using this powder and performing pressure forming using a cylindrical mold having an inner diameter of 30 cm to obtain a molded body, it was subjected to heat treatment at 1000 ° C. for 5 hours to obtain a diameter of 30 cm and a thickness of Two disc-shaped heat insulating materials having a diameter of 20 mm and a bulk density of 0.48 g / cm ³ were obtained. Using these two heat insulating materials, the thermal conductivity at 800 ° C. was measured to be 0.0943 W / m · K.

[Example 17]
After uniformly mixing 20% by mass of silica powder (small particles) with an average particle size of 14 nm and 60% by mass of silica powder (large particles) with an average particle size of 150 nm using a hammer mill, the average particle size is 1 μm. Then, 15 mass% of zirconium silicate which is an infrared opaque particle is added and mixed uniformly. Further, 5 mass% of glass fiber having an average fiber diameter of 11 μm, an average fiber length of 6.4 mm and a heat resistance temperature of 1050 ° C. The mixture was added and mixed with a high-speed shear mixer to obtain a powder. Using 702 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 17. Example 17 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 17 nm, the thermal conductivity at 30 ℃ 0.0279W / M · K, 25 heat insulating materials were cut by cutting the heat insulating material of Example 17 in the same manner as in Example 1, and none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the sample collapsed to show a breaking point when the compression rate was 4.4%, and the load at this time was 0.98 MPa. Moreover, the bulk density of the heat insulating material of Example 17 was 0.39 g / cm ³ , the pore volume was 1.247 mL / g, and R was 76.93%. Moreover, after using this powder and performing pressure forming using a cylindrical mold having an inner diameter of 30 cm to obtain a molded body, it was subjected to heat treatment at 900 ° C. for 5 hours to have a diameter of 30 cm and a thickness of Two disk-shaped heat insulating materials having a bulk density of 20 mm and a bulk density of 0.39 g / cm ³ were obtained. Using these two heat insulating materials, the heat conductivity at 800 ° C. was measured, and it was 0.0982 W / m · K.

[Example 18]
After uniformly mixing 19% by mass of silica powder (small particles) with an average particle size of 14 nm and 57% by mass of silica powder (large particles) with an average particle size of 80 nm using a hammer mill, the average particle size is 1 μm. Then, 14 mass% of zirconium silicate which is an infrared opaque particle is added and mixed uniformly, and further, 10 mass% of glass fiber having an average fiber diameter of 11 μm, an average fiber length of 6.4 mm and a heat resistant temperature of 1050 ° C. The mixture was added and mixed with a high-speed shear mixer to obtain a powder. Using 972 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 1000 ° C. for 24 hours to obtain a heat insulating material of Example 18. Example 18 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 18 nm, the thermal conductivity at 30 ℃ 0.0272W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 in Example 18, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 4.56 MPa. Moreover, the bulk density of the heat insulating material of Example 18 was 0.58 g / cm ³ , the pore volume was 1.048 mL / g, and R was 93.3%. Moreover, after using this powder and performing pressure forming using a cylindrical mold having an inner diameter of 30 cm to obtain a molded body, heat treatment is performed at 1000 ° C. for 24 hours, and the diameter is 30 cm and the thickness is increased. Two disc-shaped heat insulating materials having a diameter of 20 mm and a bulk density of 0.58 g / cm ³ were obtained. Using these two heat insulating materials, the thermal conductivity at 800 ° C. was measured to be 0.0682 W / m · K.

[Example 19]
After uniformly mixing 21% by mass of silica powder (small particles) with an average particle size of 14 nm and 63% by mass of silica powder (large particles) with an average particle size of 150 nm using a hammer mill, the average particle size is 1 μm. Then, 15 mass% of zirconium silicate which is an infrared opaque particle is added and mixed uniformly. Further, 1 mass% of glass fiber having an average fiber diameter of 11 μm, an average fiber length of 6.4 mm and a heat resistant temperature of 1050 ° C. is added. The mixture was added and mixed with a high-speed shear mixer to obtain a powder. Using 918 g of this powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Example 19. Example 19 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 16 nm, the thermal conductivity at 30 ℃ 0.0293W / M · K, 25 heat insulation materials were cut and cut in the same manner as in Example 1 in Example 19, but none of these cut insulation materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 4.96 MPa. Moreover, the bulk density of the heat insulating material of Example 19 was 0.51 g / cm ³ , the pore volume was 1.279 mL / g, and R was 77.2%. Moreover, after using this powder and performing pressure forming using a cylindrical mold having an inner diameter of 30 cm to obtain a molded body, it was subjected to heat treatment at 900 ° C. for 5 hours to have a diameter of 30 cm and a thickness of Two disc-shaped heat insulating materials having a diameter of 20 mm and a bulk density of 0.51 g / cm ³ were obtained. Using these two heat insulating materials, the heat conductivity at 800 ° C. was measured and found to be 0.0653 W / m · K.

[Example 20]
After mixing 27% by mass of silica powder (small particles) with an average particle size of 14 nm and 51% by mass of silica powder (large particles) with an average particle size of 6 μm using a hammer mill, the average particle size is 1 μm. Then, 21 mass% of zirconium silicate which is an infrared opaque particle is added and mixed uniformly. Further, 1 mass% of glass fiber having an average fiber diameter of 11 μm, an average fiber length of 6.4 mm, and a heat resistant temperature of 1050 ° C. The mixture was added and mixed with a high-speed shear mixer to obtain a powder. Using 1242 g of this powder, pressure molding was carried out in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 24 hours to obtain a heat insulating material of Example 20. Example 20 a result of the cross-section of the heat insulating material was observed as described in [Measurement of particle diameter D _S of the small particles] of equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, _{D S} is 17 nm, the thermal conductivity at 30 ℃ 0.0297W / M · K, 25 heat insulating materials were cut and cut in the same manner as in Example 1 of the heat insulating material of Example 20, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 0.75 MPa. Moreover, the bulk density of the heat insulating material of Example 20 was 0.69 g / cm ³ , the pore volume was 1.135 mL / g, and R was 48.1%. Moreover, after using this powder and performing pressure forming using a cylindrical mold having an inner diameter of 30 cm to obtain a molded body, heat treatment is performed at 900 ° C. for 24 hours, and the diameter is 30 cm and the thickness is increased. Two disc-shaped heat insulating materials having a diameter of 20 mm and a bulk density of 0.69 g / cm ³ were obtained. Using these two heat insulating materials, the heat conductivity at 800 ° C. was measured and found to be 0.0532 W / m · K.

Table 1 shows the content of Na, K, Mg, Ca, Ge, P, and Fe in the heat insulating materials of Examples 1 to 20 on the basis of the total mass of the heat insulating material. Table 2 shows the content of Na, K, Mg, Ca, Ge, P, and Fe contained in the large particles in the heat insulating materials of Examples 1 to 20 on the basis of the total mass of the large particles.

[Comparative Example 1]
Using 331 g of silica powder having an average particle diameter of 14 nm, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 24 hours to obtain a heat insulating material of Comparative Example 1. It was. The heat conductivity of the heat insulating material of Comparative Example 1 at 30 ° C. is 0.0184 W / m · K, and the heat insulating material of Comparative Example 1 is cut and cut in the same manner as in Example 1 to create 25 heat insulating materials. However, chipping and breakage were severe, and it was not possible to obtain a cut heat insulating material having a length of 6 cm, a width of 6 cm, and a thickness of 20 mm. Further, as a result of measuring the compressive strength in the same manner as in Example 1, in the range of compression rate = 0 to 5%, the sample deforms with compression and does not show a clear breaking point, and the load at the compression rate = 5% is It was 0.11 MPa.

[Comparative Example 2]
Using 1368 g of silica powder having an average particle diameter of 150 nm, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Comparative Example 2. It was. The cross section of the heat insulating material of Comparative Example 2 a result of observing as described in [Measurement of particle diameter D _S of the small particles, less particles equal area circle equivalent diameter of 5nm or more 30nm is not confirmed, the thermal conductivity at 30 ° C. The rate was 0.119 W / m · K, and 25 heat-insulating materials were prepared by cutting the heat-insulating material of Comparative Example 1 in the same manner as in Example 1. However, none of these heat-insulating materials were cut. There was no damage. Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 17 MPa.

[Comparative Example 3]
A heat insulating material was prepared in the same manner as in Example 1 except that the heat treatment was not performed, and the heat insulating material of Comparative Example 3 was obtained. The heat conductivity of the heat insulating material of Comparative Example 3 at 30 ° C. is 0.0273 W / m · K, and the heat insulating material of Comparative Example 3 was cut and cut in the same manner as in Example 1 to create 25 heat insulating materials. However, chipping or breakage was observed on 21 out of 25 sheets. Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 0.23 MPa.

[Comparative Example 4]
A silica powder in which 5% by mass of silica powder (small particles) having an average particle size of 7.5 nm and 95% by mass of silica powder (large particles) having an average particle size of 100 μm were uniformly mixed by a hammer mill was obtained. . Using 3060 g of this silica powder, pressure molding was performed in the same manner as in Example 1 to obtain a molded body, followed by heat treatment at 900 ° C. for 5 hours to obtain a heat insulating material of Comparative Example 4. Comparative Example 4 of the cross section of the insulation material [Measurement of particle diameter D _S of the small particles] result of observation as described, equal area circle equivalent diameter was confirmed 30nm or smaller particles than 5nm is 2 or more. Then, to observe the plurality of field as necessary to measure the particle size of the total of 100 small particles, the number average result this, D _S is 9 nm, the thermal conductivity at 30 ℃ 0.284W / M · K, 25 heat insulating materials were cut by cutting the heat insulating material of Comparative Example 4 in the same manner as in Example 1, but none of these cut heat insulating materials were chipped or damaged. . Furthermore, as a result of measuring the compressive strength in the same manner as in Example 1, the maximum load at a compression rate of 5.0% was 19 MPa.

[Comparative Example 5]
A silica powder in which 85% by mass of silica powder (small particles) having an average particle size of 12 nm and 15% by mass of silica powder (large particles) having an average particle size of 80 nm were uniformly mixed by a hammer mill was obtained. Using 594 g of this silica powder, pressure molding was performed in the same manner as in Example 1 to obtain a heat insulating material of Comparative Example 5. The heat conductivity of the heat insulating material of Comparative Example 5 at 30 ° C. is 0.0198 W / m · K, and the heat insulating material of Comparative Example 5 is cut and cut in the same manner as in Example 1 to create 25 heat insulating materials. However, chipping and breakage were severe, and it was impossible to obtain a cut heat insulating material having a length of 6 cm, a width of 6 cm and a thickness of 20 mm. Further, as a result of measuring the compressive strength in the same manner as in Example 1, in the range of compression rate = 0 to 5%, the sample deforms with compression and does not show a clear breaking point, and the load at the compression rate = 5% is It was 0.14 MPa.

DESCRIPTION OF SYMBOLS 1 ... Heat insulation material enclosure, 2 ... Heat insulation material, 3 ... Cover material, S ... Small particle, L ... Large particle.

Claims

Comprises silica and / or alumina, and the particle diameter D S are molded include a plurality of small particles is 5nm or more 30nm or less, the maximum load in the compression ratio 0-5% is 0.7MPa or more, 30 ° C. A heat insulating material having a thermal conductivity of 0.05 W / m · K or less.
The heat insulating material according to claim 1, wherein the bulk density is 0.2 g / cm 3 or more and 1.5 g / cm 3 or less.
The heat insulating material according to claim 1 or 2, wherein the pore volume is 0.5 mL / g or more and 2 mL / g or less.
The ratio R of the cumulative pore volume V of pores having a pore diameter of 0.05 μm or more and 0.5 μm or less to the cumulative pore volume V 0.003 of pores having a pore diameter of 0.003 μm or more and 150 μm or less is 70. The heat insulating material according to any one of claims 1 to 3, which is at least%.
The heat insulating material according to any one of claims 1 to 4, comprising infrared opaque particles and having a thermal conductivity at 800 ° C of 0.2 W / m · K or less.
The infrared opaque particles have an average particle size of 0.5 μm or more and 30 μm or less, and the mass content of the infrared opaque particles is 0.1% by mass or more and 39.5% by mass based on the total mass of the heat insulating material. The heat insulating material of Claim 5 which is the following.
Comprises silica and / or alumina, further comprising, the ratio R L is 60 mass of the mass of the large particles to the total mass of the mass and large particles of small particles a plurality of large particle diameter D L is 50nm or more 100μm or less The heat insulating material according to any one of claims 1 to 6, which is not less than 90% and not more than 90% by mass.
Contains at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements and germanium, and contains at least one element selected from the group consisting of the alkali metal elements and alkaline earth metal elements When the content is 0.005 mass% to 5 mass% based on the total mass of the heat insulating material, and when germanium is contained, the content is 10 mass based on the total mass of the thermal insulating material. The heat insulating material according to any one of Claims 1 to 7, wherein the heat insulating material is not less than ppm and not more than 1000 mass ppm.
The heat insulating material according to claim 7 or 8, wherein the large particles contain at least one element selected from the group consisting of the alkali metal element, the alkaline earth metal element, and germanium.
The heat insulating material according to any one of claims 1 to 9, further comprising an inorganic fiber, wherein the content of the inorganic fiber is more than 0% by mass and 20% by mass or less based on the total mass of the heat insulating material.
The heat insulating material according to any one of claims 1 to 10, comprising phosphorus, wherein the phosphorus content is 0.002% by mass or more and 6% by mass or less based on the total mass of the heat insulating material.
The heat insulating material according to any one of claims 1 to 11, which contains iron, and the iron content is 0.005 mass% or more and 6 mass% or less based on the total mass of the heat insulating material.
The heat insulating material according to any one of claims 1 to 12, which is housed in a jacket material.
The heat insulating material according to claim 13, wherein the jacket material includes inorganic fibers or the jacket material is a resin film.
Containing an inorganic mixture containing silica and / or alumina and containing small particles having an average particle diameter of 5 nm to 30 nm in a mold; and
A molding step of molding the inorganic mixture,
The said formation process is a manufacturing method of a heat insulating material which has the following process (a) or process (b).
(A) The process of heating to 400 degreeC or more, pressing the said inorganic mixture with the said shaping | molding die.
(B) A step of performing heat treatment at a temperature of 400 ° C. or higher after forming the inorganic mixture by pressurization.
The method for producing a heat insulating material according to claim 15, wherein the inorganic mixture further includes large particles containing silica and / or alumina and having an average particle diameter of 50 nm or more and 100 µm or less.
The step of mixing the small particles and the large particles at a ratio R L of the mass of the large particles to the sum of the mass of the small particles and the mass of the large particles in a range of 60% by mass to 90% by mass to obtain an inorganic mixture. Furthermore, the manufacturing method of the heat insulating material of Claim 16.
The method for producing a heat insulating material according to claim 16 or 17, wherein the large particles contain at least one element selected from the group consisting of the alkali metal element, alkaline earth metal element, and germanium.
The heat insulation according to any one of claims 15 to 18, wherein, in the molding step, a molding pressure is set so that a bulk density of the molded heat insulating material is 0.2 g / cm 3 or more and 1.5 g / cm 3 or less. A method of manufacturing the material.
The method for manufacturing a heat insulating material according to any one of claims 15 to 19, further comprising a cutting step of cutting a part of the formed body obtained by the forming step.